by Jack McKillop
The Mariana Islands are a group of 15 islands in the Western Pacific Ocean located between 12° to 21°N and 144° to 146°E. The total land area of these islands is 393-square-miles (1,018-square-kilometers). The main islands, Guam, Saipan and Tinian, are located in the south of this chain. These three islands are about 1,500-miles (2,414-kilometers) south of Tokyo, Japan; 3,700-miles (5,955-kilometers) west of Pearl Harbor, Territory of Hawaii; 1,200-miles (1,931-kilometers) north of New Guinea; and 1,300-miles (2,092-kilometers) east of the Philippine Islands.
The first European to visit the Marianas was the Spanish explorer Ferdinand Magellan in 1521. Spain claimed the islands in 1667 and they were named Las Marianas in 1668 in honor of Queen regent Mariana of Austria, the widow of King Philip IV of Spain.
The islands remained a Spanish colony under the general government of the Philippines until 1898, when, as a result of the Spanish-American War, Spain surrendered the island of Guam to the United States. In 1899, Spain still controlled about 6,000 islands in the Pacific in the Caroline, Marianas and Palau Islands. All were sold to Germany and incorporated as a small part of the larger German Protectorate of New Guinea.
When World War I began in 1914, the Japanese formally declared war on the German Empire on 23 August 1914 and began occupying the 14 German possessions in the Mariana Islands. In 1920, the Japanese were given a League of Nations mandate over these islands; Guam remained a U.S. possession.
In the spring of 1944, the Joint Chiefs of Staff (JCS) in Washington ordered that Guam, Saipan and Tinian in the Mariana Islands be occupied “with the object of controlling the eastern approaches to the Philippines and Formosa (now Taiwan), and establishing fleet and air bases.” Saipan and Tinian would be developed to accommodate U.S. Army Air Forces B-29 Superfortresses to bomb the Japanese home islands while Guam would be developed as the Navy’s most important fleet base in the western Pacific.
In 1947, the United Nations established The Trust Territory of the Pacific Islands to be administered by the United States and the 14 Northern Mariana Islands became part of the Trust Territory. In 1976, the U.S. Congress approved the mutually negotiated Covenant to Establish a Commonwealth of the Northern Mariana Islands (CNMI) in Political Union with the United States; the people of Guam declined to join CNMI. The CNMI Government adopted its own constitution in 1977, and the constitutional government took office in January1978. The Covenant was fully implemented on 3 November 1986, pursuant to U.S. Presidential Proclamation No. 5564, which conferred United States citizenship on legally qualified CNMI residents.
On 22 December 1990, the Security Council of the United Nations terminated the TTPI as it applied to the CNMI.
Guam, Naval Operating Base
Guam (13°26'N, 144°46'E) is the largest, most populous island in the Mariana Islands. The island is about 32-miles (51-kilometers) long and varies in width from 4-miles (6.4-kilometers) near the center portion to about 12-miles (19-kilometers); the total land area is 209-square-miles (543-square-kilometers). The entire island is surrounded by an extensive reef system.
The northern portion of the island is a high limestone plateau with an average elevation of 400 feet (122-meters), broken only by two higher points, Mt. Santa Rose (830-feet or 253-meters) and Mt. Barrigada (650-feet or 198-meters). The northern clifflines drop precipitately into the sea with an elevation ranging from 300-to-600-feet (91-to-183-meters). In general, the plateau is gently rolling and well adapted for the construction of airfields and related facilities.
The southern part of the island has a rugged terrain with red volcanic clay soil which becomes very unstable under heavy rains. The highest point on the island is Mount Lamlam in the south rising to a height of 1,332-feet (406-meters).
The only important anchorage is Apra Harbor (13°27'N, 144°39'E), on the western side of the island, formed by Cabras Island and Orote Peninsula. In spite of these protective arms, however, the harbor was open to heavy ocean swells and required considerable development before it could be considered a first-class anchorage.
The Department of the Navy administered Guam as per an executive order by U.S. President William McKinley. The Navy established a facility near the village of Piti (13°27' 36"N, 144°41' 30"E) on the shores of Apra Harbor in 1899, and the U.S. Marine Corps opened a barracks at Sumay (13°25' 31"N, 144°38' 58"E) on the south shore of Orote Peninsula in 1901. A naval coaling station was established on Cabras Island in 1905, and a battery of six 6-inch (152-millimeter) guns were emplaced on the western tip of Orote Peninsula to strengthen Guam's defenses in 1909.
In the first decade of the 20th Century, Guam became a hub of transpacific telegraph submarine cables. The first connected San Francisco, California and Manila, Philippine Islands via Honolulu, Hawaii, Midway Islands and Guam. A second connected Guam with Menado, Celebes Island, East Indies via Yap Island in the Caroline Islands. In 1942, the Japanese diverted this latter cable to the Palau Islands in the Caroline Islands.
In 1906, a 1,102-mile (1,806-kilometer) cable was laid between Guam to Chichi Jima in the Bonin Islands; this system connected to a cable laid to Japan in 1905.
In 1921, Flight “L” of the Marine Fourth Air Squadron was ordered to the Marine Barracks at Sumay. This flight was equipped with Curtiss HS-2Ls and N-9s and Naval Aircraft Factory F-5Ls; later, they were equipped with Vought VE-7Hs. All of these aircraft were biplane seaplanes. In 1926, this flight was redesignated Marine Scouting Squadron One (VS-1M) and redesignated Marine Patrol Squadron Three (VP-3M) in July 1927. By 1928, the squadron was flying Loening OL-3s, -6s and -8s.
In 1922, the Washington Naval Treaty was signed by France, Italy, Japan, the United Kingdom and the U.S. The treaty called for each of the countries involved to maintain a set ratio of warship tonnage. The treaty also forbade the U.K. and U.S. from building new fortifications and certain other types of facilities in the Far East. That left the Philippines less fortified than the U.S. wanted them to be, and left Guam essentially defenseless. On 29 December 1934, the Japanese government gave formal notice that it intended to terminate the treaty. Its provisions remained in force until the end of 1936, and it was not renewed, Japan effectively leaving the treaty in 1936.
Between 1930 and 1932, the battery of six 6-inch (152-millimeter) guns had been removed, the Marine patrol squadron was transferred to the U.S. and decommissioned in February 1931 and the Marine garrison was reduced to ten officers and 121 enlisted men.
As early as 1931, Pan American Airways (PanAm) began planning for air service from the U.S. to the Orient. By the end of 1934, PanAm’s plans were finalized. The flights would fly from Alameda, California, to the British Crown Colony of Hong Kong via Honolulu, Territory of Hawaii; Midway Island; Wake Island; Guam; and Manila, Philippine Islands. Construction of bases on Guam, Midway and Wake began in April 1935. These island bases consisted of an attractive hotel that was lawned and landscaped and had electricity, food, showers, solar water heaters, terrace furniture, bridge tables and beach umbrellas, along with support buildings, long-distance direction-finding (DF) equipment and aviation fuel. On 22 November 1935, a PanAm Martin Model 130 flying boat made the first scheduled air mail flight between Alameda and Manila in 59 hours 48 minutes. The first passenger flight from Alameda to Manila took off on 21 October 1936; the fare was US$950 (US$15,437 in 2011 dollars). Service to Hong Kong was authorized in September 1936 and service from Manila to Hong Kong began in January 1937.
In 1939, the U.S. Congress approved a bill which would authorize the construction of certain aviation facilities on Guam. These included US$2.2 million (US$37.7 million in 2011 dollars) to build a breakwater, US$1.9 million (US$308.5 million in 2011 dollars) to dredge the harbor, remove coral heads, to provide a channel for ships and for seaplane operations, and US$900,000 (US$14.6 million in 2011 dollars) to build seaplane ramps and parking space, a small power plant and necessary accessories.
Early in 1941, a contract with a civilian construction company was negotiated for the construction of a naval station at Guam. Construction work was limited to tank farms for fuel oil, diesel oil, and motor gasoline; additional seaplane facilities; together with housing, power, water, and roads. Construction began in May 1941 with the erection of five steel tanks for oil storage, and the next project was road construction. Construction on the breakwater on Luminao Reef on the western tip of Cabras Island, to afford greater protection against typhoons was not started until August 1941. Huge limestone blocks, quarried on Cabras Island, were skidded along the reef to an improvised derrick which deposited them at desired points to form the breakwater. Other construction work included the oil pier and the development and extension of power, water, communications, and sewage-disposal system. By December 1941, a road had been extended and improved; 1-mile (1.6-kilometer) of breakwater, 36-feet (11-meters) wide and 5-feet (1.5-meters) above sea-level, had been completed. An oiling dock had been constructed and piped, and some work had been accomplished on pump houses, barracks, and mess halls.
The contractor's organization had also done engineering and experimental work in connection with a proposed Orote Peninsula airfield. In a letter of 6 August 1941, the naval commandant reported surveys indicating that a 4,500-by-400-foot (1,372-by-132-meter) landplane runway could be constructed. No action was taken by the U.S. on this proposal.
By December 1941, there were 271 Navy personnel, 122 Marines and five Navy nurses on the island; there was also 80 Guamanians that were part of the Guam Insular Force Guard which was a locally-manned milita force responsible for protecting the naval base. On 8 December 1941 (7 December in Hawaii), Japanese aircraft bombed the Marine barracks, fuel storage tanks and the PanAm Hotel and damaging a minesweeper and a miscellaneous auxiliary. The following day, a Japanese destroyer shelled Agana, the largest city on Guam with a population of about 10,000, nearly half of the island's residents, and Japanese aircraft again attacked. At 0215 hours local on 10 December, the Japanese landed near Agana. After token resistance, the governor surrendered at 0700 hours.
The five Navy nurses continued caring for casualties at the Naval Hospital on Guam until 10 January 1942 when they were transported to Japan. Held for three months in the Zentsuji Prison on Shikoku Island, they were moved to the Eastern Lodge in Kobe on 12 March until brought to Mozambique, Portugese South Africa, on 25 August 1942 aboard a Japanese ship. Waiting there was the Swedish-America line ship SS Gripsholm which had arrived from the U.S. The five nurses, which were part of an exchange of diplomatic personnel, arrived in New York City on 29 August. No other U.S. prisoners of war were exchanged.
Although the U.S. never built an airfield on the Orote Peninsula, the Japanese recognized the suitability of the location and constructed, a 4,500-foot (1,372-meter) coral-surfaced airstrip on the peninsula (13°26' 13"N, 144°38' 23"E). This was known as Guam Number 1 by the Japanese. In addition, the Japanese brought a similar strip, known as Guam Number 2 (13°29' 06"N, 144°47' 51"E) northeast of Agana to near-completion and partially cleared a third strip, known as Guam Number 3 (13°32' 12"N, 144°49' 20"E) still farther north. Otherwise, the Japanese did very little to improve or extend the island facilities.
On 22 February, 1944, aircraft from the Navy’s Task Force 58 bombed Guam, in the first strike against the Marianas. This was followed on 3 March 1944 by U.S. Army Air Forces B-24 Liberators making their first bombing raid on Guam. These strikes continued until the invasion of Guam including a strike on 12 June 1944 when aircraft from 15 carriers worked over Japanese air facilities and coast defenses on Saipan, Tinian, Guam, Rota, and Pagan Islands. Marianas. Carrier strikes are repeated on 13 and 14 June in preparation for the landings on Saipan.
The U.S. invasion of Guam was scheduled for 18 June 1944 but on 16 June, Admiral Raymond Spruance, Commander of the Fifth Fleet, postponed the landings indefinitely since a major naval battle appeared to be imminent. He was correct. On 19 and 20 June, the U.S. Navy engaged the Japanese in the Battle of Philippine Sea, commonly known as The Marianas Turkey Shoot. The invasion finally occurred on 21 July with Army and Marine troops landing north and south of Apra Harbor. Organized Japanese resistance ended on 10 August but enemy resistance from caves, jungles, and hillsides continued for many weeks.
Of prime importance was the establishment of five airfields to support the offensive operation of U.S. Army Air Forces’ (USAAF) B-29 Superfortresses against the Japanese Home Islands. The three Japanese airstrips, which had been captured in varying stages of completion, formed the nucleus of the first three fields to be established. In addition, two huge fields of two runways each were constructed on the northern tip of the island.
Army, Navy and Marine engineer units began work immediately to repair and update facilities on the island. The Japanese airstrip on Orote Peninsula (Guam Number 1 at 13°26' 13"N, 144°38' 23"E) had been cleared of enemy resistance on 28 July and was placed in operation the next day.
Orote Field, which had been completed by the Japanese to 4,500-feet (1,372-meters), and was the only existing strip to be rehabilitated during the assault, was completely rebuilt and lengthened to 5,500-feet (1,676-meters) by Marine Engineers. Seabees assisted in the development of the field, constructing hardstands, shops, and warehouses. The first aircraft landed at Orote Field on 29 August 1944 and it was in constant use, first for fighter operations and later for conditioning 1,800 planes per month for the Fleet and the Marines. Planes were tested, repaired, and cleaned of the preserving compounds with which they had been shipped overseas. An aviation supply depot and an aircraft repair and overhaul unit were established at the field. The facility was established as Naval Air Base Guam on 21 October 1944.
The second step in airfield construction was on the 5,000-foot (1,524-meter) Guam Number 2 (13°29' 06"N, 144°47' 51"E) airstrip which the Japanese had almost completed near Agana. The initial runway was extended to 7,000-feet (2,134-meters) and paved with asphalt, and a second asphalt-surfaced strip, 150-by-6,000-feet (46-by-1,829-meters), was constructed. The field was rotated several degrees in order to reduce flight interference from Mt. Barrigada. Agana Field, as it was named, was used principally by the USAAF Air Transport Command (ATC) and B-24 Liberator bombers and the Naval Air Transport Service. Guam soon became a major base for the ATC.
The Japanese had completed clearing a third airstrip, to the north of Agana Field, Guam Number 3 (13°32' 12"N, 144°49' 20"E). This site was chosen for the establishment of Depot (later, Harmon) Field, and again the orientation was shifted slightly. Two inches (5.1 centimeters) of asphaltic concrete were applied to the 7,000-by-150-foot (2,134-by-46-meter) airstrip and 12,000-feet (3,658-meters) of taxiway and 42 hardstands were constructed. Eight superstructure hangars, 130-by-160-feet (40-by-90-meters) each, and ten 160-by-190-foot (49-by-55-meter) repair hangars were erected for the field. Cooperation between the Army Engineers and the Seabees produced the largest air repair base in the Pacific for the repair of B-29s in the Mariana Islands. The first B-29s landed on 24 November 1944.
Early in 1945, attention was concentrated on the carving of the two B-29 fields, North and Northwest Fields, out of the dense jungle on the northern end of Guam. Each field comprised two asphalt-surfaced runways, 8,500-by-200-feet (2.591-by-61-meters), capable of sending off 160 planes per flight. North Field (13°34' 58"N, 144°55' 38"E) was constructed entirely by Army Engineers. The first airstrip was commissioned on 3 February 1945, and three weeks later, the first B-29 Tokyo raid from Guam was launched from this airstrip. By the end of April, the second runway was in operation.
During April and May 1945, the combined efforts of the Army Engineers and the Seabees were centered on the construction of Northwest Field (13°37' 24"N, 144°51' 28"E). In the construction, 26-foot (7.9-meter) cuts and fills were made through hard limestone. The south runway, completed two days ahead of schedule, was opened to service on 1 June 1945. Work was rushed on the taxiways, hardstands, and operational facilities for the south strip and also on the second airstrip and its appurtenances to accommodate the rapidly arriving B-29s. The north runway was in operation by 1 July.
Development of waterfront facilities in Apra Harbor was a task of highest priority. The tremendous importance of the harbor to base development had been recognized in the choice of an assault site. The Seabees began the installation of pontoon piers to break a prospective bottle-neck of supply. By the first of October 1944, six piers, 42-by-350-feet (13-by-107-meters), were in full operation, and a seventh was under way. Then disaster struck. A full-scale typhoon passed near Guam between 3 and 9 October. Continued strong winds built up such heavy waves in Apra Harbor that they destroyed or severely damaged all the pontoon piers, carried away portions of the Cabras Island breakwater, and seriously damaged the sunken barges placed to form the breakwater extension. One month after the typhoon, seven piers were again in full operation and in a more secure condition. By July 1945, the piers in Apra Harbor numbered 14 quay-wall berths, nine pontoon piers, two wooden piers for fueling, ten landing ship, tank (LST) berths, and one submarine pier.
As the waterfront facilities were developed to accommodate the heavy flow of supplies and equipment, other construction on Guam proceeded apace.
Due to the position of Guam in the forward area, it was essential that a large store of supplies, spare parts, equipment, fuels, and refrigerated foods be on hand at all times for the Fleet and for military forces on the island and in forward movements. By March 1945, an extensive tank-farm system was completed. Storage had been provided for 328,000 barrels of aviation gasoline, 130,000 barrels of diesel oil, 40,000 barrels of motor gasoline, and 448,000 barrels of fuel oil. (NOTE: A barrel is equal to 42 U.S. gallons, 35 Imperial gallons or 159 liters.) Several major supply depots were established. The naval supply depot comprised 464 steel arch-rib warehouses, a large personnel camp, open storage areas, a drum filling plant, and 68,000-cubic-feet (1,926-cubic-meters) of refrigerator storage. The advance base construction depot covered 250 acres (101 hectares) and had 360 buildings for general warehouses, spare parts storage, equipment overhaul and tire repair, and a 2,600-man camp. The function of the depot was to procure, store, and issue supplies and equipment, primarily for the Seabees, but equipment was issued to other military activities when available and if priorities warranted the issue.
Naval Operating Base Guam, was established on 20 October 1944 and eventually had floating dry docs with lifting capacity up to 80,000 tons (72,575 metric tonnes) and shops capable of repairing all types of ships.
The Marines had cognizance of the issue of all the staple foods on the island, which necessitated large warehouses. Five 96-by-540-foot (29-by-165-meter) buildings were erected at Agana, and two at Agat, one 745-by-118-feet (227-by-36-meters) and the other 349-by-118-feet (106-by-26-meters), for this purpose. The medical supply depot was composed of 18 buildings. Total warehouses for all airfields consisted of more than 1 million square-feet (92,903 square-meters) of space. The Marine depot for supplies was made up of 190 buildings. Army garrison forces had about 600,000 square-feet (55,742 square-meters) of storage space.
The naval ammunition depot, which covered 6,910 acres (2,795 hecares), consisted of two sections, one for the Fleet and one for ground forces. The Fleet unit comprised 44 Quonsets for personnel and administration buildings, 202 prefabricated steel magazines, 100 hardstands, and 20 fuse magazines. The ground units had 26 Quonset huts, 550 shelters, 61 hardstands, and 50 magazines.
The water system on Guam at the time of the invasion was insufficient, because of bombardment damage and initial inadequacy, to meet the needs of the tremendous increase in population and the demands of the Fleet. Various methods were used in the development of an adequate water system. Shallow wells along the coastal areas, deep wells in the interior, a basal ground-water tunnel, dams, and springs were used until the total completed water system had a capacity of 12 million U.S. gallons (10 million Imperial gallons or 45.4 megaliters) per day from 67 main sources.
Hospital construction on Guam was initiated in September 1944. By March 1945, the hospitals, brought to usable completion by Seabees and Army Engineers, provided a total of about 9,000 beds and were pressed into service to handle casualties from the Iwo Jima operation. Included were Naval Base Hospital 18 (1,000 beds); Fleet Hospital 103 and 115 (1,000 and 2,000 beds, respectively); the 373rd Army Station Hospital (750 beds); and the 204th Army General Hospital (1,000 beds).
In all, some 37,000 construction troops were employed in the construction of Advance Base Guam.
In 1950, the Guam Organic Act, established Guam as an unincorporated organized territory of the U.S., provided for the structure of the island's civilian government, and granted the people U.S. citizenship. Since Guam is not a U.S. state, U.S. citizens residing on Guam are not allowed to vote for president and their congressional representative is a non-voting member. Guam is governed by a popularly elected governor and a unicameral 15-member legislature, whose members are known as senators. Guam elects one non-voting delegate to the U.S. House of Representatives.
The status of the five World War II airfields on Guam in 2011 is:
Saipan, Naval Air Bases and Naval Operating Base
Saipan (15°11'N, 145°44'E) is the second largest island in the Mariana Islands with a total land area of 45-square-miles (115-square-kilometers). The island is about 120-miles (190-kilometers) north of Guam and about 3-miles (4.8-kilometers) northeast of Tinian Island with a strait separating them. The island is about 12-miles (19-kilometers) long and 5.6-miles (9.0-kilometers) wide.
The western side of the island is lined with sandy beaches and an offshore coral reef which creates a large lagoon. The eastern shore is composed primarily of rugged rocky cliffs and a reef. The highest point on the island is a limestone covered Mount Tapochau at 1,560-feet (480-meters). Undeveloped areas on the island are covered with sword grass meadows and dense, dry-forest jungle known as Tangan-Tangan.
Starting in 1922, the Japanese developed both fishing and sugar industries, and in the 1930s garrisoned Saipan heavily, resulting in nearly 30,000 troops on the island by 1941. By December 1941, Saipan had a population of more than 30,000 people, including 25,000 Japanese settlers, many of them from Okinawa.
The U.S. Strategic Bombing Survey said, “Almost unanimously, informed Japanese considered Saipan as the decisive battle of the war and its loss as ending all hope for a Japanese victory.” Thus, on 15 June 1944, Saipan was the first island in the Mariana Islands to be invaded by U.S. forces. The 2nd and 4th Marine Divisions landed in the southwest of the island and the elements of the Army’s 27th Infantry Division landed days later. They faced 31,600 Japanese troops and the Japanese fortifications were formidable. By 1 July, American troops had captured the central part of the island around Mt. Tapotchau, gained control of the heights commanding Garapan and Tanapag Harbor on the west coast, and advanced to within 5-miles (8-kilometers) of the northern tip of the island. Organized Japanese resistance ended on 9 July.
The Japanese had built three airfields and a seaplane base on the island. Aslito Airfield (15°07' 12"N, 145°43' 45"E), the main base located on the south of the island in 1934; Marpi Point Airfield (15°16' 51"N, 145°48' 56"E) a fighter base with one 4,380-foot (1,335-meter) runway at the northern end of the island; and Susup Airfield (15°09' 39"N, 145°42' 22"E) with a single 3,875-foot (1,181-meter) north-south runway as an emergency airfield on the southwestern part of the island. Tanapag Seaplane Base (15°13' 50"N, 145°44' 22"E) was located in the northern portion of Tanapag Harbor, near Garapan and Tanapag off the west coast of Saipan and had been built in 1935. This base had been developed as a seaplane base for the long-range Japanese four engine Emily flying boats (Kawanishi H8K, Navy Type 2 Flying Boats) and had been heavily bombed before the invasion.
Aslito Airfield (15°07' 12"N, 145°43' 45"E) was captured by Army troops on the night on 16/17 June. The airfield was initially named Conroy Field on 18 June but was subsequently renamed Isley Field in honor of Navy Commander Robert H. Isely who was killed on 13 June 44 while strafing the base Note that the commander’s name was spelled Isely but usage has misspelled his name and Isley now appears in official documentation.
After the airfield had been captured, a Japanese Zeke fighter (Mitsubishi A6M, Navy Type 0 Carrier Fighter) from Guam landed at the airfield; the pilot was unaware that the field had fallen to the Americans. As it landed it was fired upon and it crashed at the end of the airstrip. The pilot survived and the plane was captured.
The airfield had been damaged by shells and was covered with shrapnel. It was decided that the northern side of the runway was easiest to repair, and the next day, the Seabees began work. Holes were filled with coral from stockpiles found near the edge of the field and two Japanese road-rollers were found and put into operation. By the end of the second day, the entire
4,500-by-150-feet (1,372-by-46-meters) strip had been repaired and the first plane, a Navy TBF Avenger, landed. By D-plus-six, the runway had been widened to 200-feet (61-meters). On 22 June, U.S. Army Air Forces (USAAF) P-47D Thunderbolts were catapulted from two Navy escort aircraft carriers and landed at the airfield to provide air defense and close air support for ground troops. Two days later, P-61 Black Widow night fighters arrived.
Isley Airfield had been designated as one of two B-29 Superforess bases on Saipan and extensive construction was required to accommodate these aircraft. The single runway was extended to 8,500-by-200-feet (2,591-by-61-meters) along with extensive taxiways and revetments which were located to the north and south of the runway. A second runway was constructed and completed in early 1945. The first B-29 arrived at Isley Field on 12 October 1944; the first mission was flown on 28 October to Dublon Island, Truk Atoll, Caroline Islands. On 24 November, 111 B-29s took off from Isley Field heading for Japan; 88 bombed targets in the Tokyo area.
After the war, the airfield was returned to civil control and reverted back to being called Aslito Field. By December 1975, it had been rebuilt and renamed Saipan International Airport. In 2005, the airport was also renamed for former Lieutenant Governor Francisco C. Ada.
The Seabees began the reconstruction of the former Japanese Marpi Point Field (15°16' 51"N, 145°48' 56"E), also known as North Field, in January 1945 and had nearly completed the facilities by the end of April when the balance of assigned construction was turned over to the USAAF aviation engineers. When completed, Naval Air Base Marpit Point had a 4,500-foot (1,372-meter) runway, 15,000-feet (4,572-meters) of taxiways and parking areas, 45 buildings, and several portable hangars. By the end of July, the field had been increased to include a second runway, 3,500-feet (1,067-meters) long, and a 1,400-foot (427-meter) addition to the original runway. This airfield was used by Navy and Marine fighters.
On 11 October 1944, Seabees began work on the former Japanese seaplane base at Tanapag. They found the site littered with wrecked aircraft, wrecked masonry buildings, the twisted steel framework of hangars, a damaged concrete seaplane ramp, and a demolished concrete apron. The badly damaged buildings were destroyed and the area cleared of wreckage. Work was pushed to make major repairs to the ramp and parking area, to secure adequate drainage, and to increase the operating area. Housing was provided for 1,750 men in Quonset huts, and a 100-bed dispensary was erected. Quonset huts and steel arch-rib buildings were built for shops, and two portable seaplane hangars were provided. By the end of January 1945, all work under the original plan for the base had been completed. During April and May, facilities were expanded to include an aviation supply annex, an aviation repair unit, and additional housing for 2,500 men. Expansion of the base also required drainage of a swamp.
Naval Air Station (NAS) Tanapag was established on 1 October 1944. Several of the patrol bomber seaplane squadrons were stationed at Tanapag during the war including two that flew Consolidated PB2Y-5 Coronados from the harbor. After the war the decision was made to concentrate all naval facilities at NAS Guam.
The Japanese Susup Airfield was not used by U.S. troops.
Two additional airfields were built by USAAF aviation engineers on the island, Kobler Airfield and Kagman Airfield.
Kobler Airfield (15°07' 22"N, 145°42' 15"E) was located about 1.9-miles (3.1-kilometers) west-northwest of Isley Field. The original plan was to develop Kobler as an operational B-29 base but the plan was changed and a second runway was added at Isley Field. As a result, a 7,000-foot (2,134-meter) runway was built at Kobler and the field was used for temporary storage of up to 60 B-29 spare aircraft and operations by B-24 Liberators and Navy PBY-5A Catalinas. Following World War II, commercial airlines used Kobler Field as an airport. In 1968, it was decided to move the commercial airport to Isely Field. New construction began in 1972 and on 15 December 1975 the first commercial aircraft landed at the renamed Saipan International Airport, initiating a new historic Isely Field. Today, the land has been converted to housing developments.
Kagman Airfield (15°10' 05"N, 145°46' 36"E), also known as East Field, was built as a base for USAAF heavy bombers and fighters. The airfield's facilities included a single runway 5,100-by-150-foot (6,208-by-241-meter) running east to west. An extensive taxiway and revetment area was located on the north and south sides of the runway. The first units to arrive were equipped with B-24s and C-47 Skytrains on 4 August. By February 1945, the Liberators were gone and the base was occupied by fighters, photographic reconnaissance and transport aircraft. In April 1945, the Seabees were assigned to the partial construction and revision of the field. The existing coral-surface strip, was repaved, and additional facilities were built, including two portable hangars, a 1,000-man mess hall and 58 Quonset huts for quarters, shops, and utilities. By mid-1946 most USAAF units at Kagman Field were reassigned, and the military use of the airfield ended. It was used as an airport until the mid-1960s when it was closed and the land redeveloped with housing and a golf course.
On 21 June, the Seabees were ordered to repair the railroad from Chalon Kanoa (15°09' N, 145°42' E) to Aslito Field, which had been badly damaged by shell fire. Four days later, the first train ran to the airfield. Other railroads were soon repaired and running smoothly, and the Seabees then turned to road repair.
Naval Operating Base (NOB) Saipan was established on 1 September 1944. On 13 September, the commander of the naval base presented to the island commander a plan for the development of a naval base, to include housing, boat-repair facilities, a tank farm, a naval supply depot, a naval hospital, an ammunition depot, fleet recreation areas, and general harbor developments.
Construction of a tank farm to supply fuel, diesel oil, and aviation gasoline for the Fleet as well as aviation gasoline for the seaplane base was started 16 October 1944. The tank farm was to consist of eighteen 1,000-barrel tanks for aviation gasoline, seven 10,000-barrel tanks for diesel fuel, and fifteen 10,000-barrel tanks for fuel oil, together with connecting pipelines, pump housing, and 1,200-feet (366-meters) of submarine line for each type of fuel. The work was greatly delayed by the lack of material. By the end of November, however, the tanks and lines for aviation gasoline had been completed. By August 1945, seven of the fifteen 10,000-barrel oil tanks were in operation and the balance ready for tests; three of the original diesel tanks were in operation and the other four under construction. All lines from tanker moorings to the tank farms were completed in March 1945.
In October 1944, construction of a naval supply depot began, which was to support the Fleet and shore-based personnel in the area. Two 100-by-300-foot (30-by-91-meter) transit sheds were rushed to completion to provide for 2,500 tons (2,268 metric tonnes) of supplies due early in November. The supply depot, completed in February 1945, consisted of 64 steel arch-rib warehouses, 11 refrigerator sheds, and eight Quonset huts for administration.
Another task of the Seabees was the erection of their own permanent camps and naval base housing for 3,200 men. The project included two 1,500-man galleys and mess halls. Ten double-deck barracks and an office were constructed adjacent to the housing development for use as a receiving barracks.
Before development of the naval base, waterfront facilities at Tanapag Harbor consisted of three berths for Liberty ships at an existing masonry pier and two 12-by-72-foot (3.7-by-22-meter) pontoon piers. The concrete ramp at the seaplane base was used for the discharge of landing ships, tank (LSTs), landing craft, tank (LCTs) and landing craft, mechanized (LCMs).
The naval base plan called for the establishment of a mobile repair facility sufficient to maintain and repair hulls and engines of craft assigned to small-boat repair units and a small-boat pool.
The mobile amphibious base repair unit consisted of five steel arch-rib buildings, one 3-by-7-foot (0.9-by-2.1-meter) pontoon barge, one 4-by-7- foot (1.2-by-2.1-meter) pontoon barge with a 12-ton (11-metric-tonne) crane, one 6-by-18-foot (1.8-by-5.5-meter) pontoon drydock with a 4-by-7-foot (1.2-by-2.1-meter) pontoon tender barge, three 2-by-24-foot (0.6-by-7.3-meter) pontoon piers, and two 30-ton (27-metric tonne) ramps. Fuel storage for this unit was provided in four 10,000-barrel diesel-oil tanks and two 1,000-barrel aviation-gasoline tanks.
The small-boat repair unit included one steel arch-rib building, two 2-by-12-foot (0.6-by-3.7-meter) pontoon barges, and one 4-by-6-foot (1.2-by-1.8-meter) pontoon wharf, and a 4-by-15-foot (1.2-by-4.6-meter) pontoon drydock, two Quonset huts, and mobile machine shops.
A small-boat pool and landing vehicle, tracked (LVT) repair facilities were constructed on the site of an existing Japanese boat-basin. The Garapan pier, which had been partially repaired during the assault phase of operations, was further improved by putting in additional piling and coral-fill to provide 1,900 lineal feet (579-meters) of marginal pier, During the spring of 1945, two 7-ton (6.4-metric tonne) cranes were erected on 6-by-18-foot (1.8-by-5.4-meter) pontoon barges and constructed an ammunition pier at Garapan, together with a 900-by-22-foot (274-by-6.7-meter) earth and coral causeway.
An industrial area, established in the spring of 1945 consisted of eight Quonset huts and nine steel arch-rib buildings, with access roads and utilities. Three steel arch-rib buildings and two Quonset huts provided shops for the repair of base equipment.
An ammunition area involved the construction of 112 steel magazines, 20-by-50-feet (6.1-by-15-meters), each; four torpedo magazines; shops and a motor-maintenance shed; coral-surfaced bunkers and parking areas; and more than 6-miles (9.7-kilometers) of access roads.
Naval medical facilities at Saipan were provided by small dispensaries at individual naval activities and one 400-bed hospital constructed early in 1945. The hospital unit contained 40 Quonset huts for wards, laboratories, mess halls, galleys, quarters, and administration buildings. Two steel arch-rib buildings with concrete decks and a refrigerator were constructed for general medical storage. The hospital was used for casualties from the Iwo Jima and Okinawa campaigns.
The major medical installations on Saipan were for the Army, and the Seabees assisted in the construction of several Army hospitals. In March 1945, the Seabees were ordered to construct Convalescent Hospital No. 5, a 3,000-bed unit of tents with wooden decks. Work was started on 25 March, and 1,000 beds with necessary facilities were ready eight days later. The hospital was completed on 28 April.
On 14 March 1945, the Seabees were assigned the completion of the 2,000-bed General Hospital 148, which had been under construction by the Army for seven months. The work remaining to be accomplished was the erection of 45 Quonset huts, 20 prefabricated huts, all utilities, and improvements to galleys and mess halls. The Seabees, with aid from 180 men of an Army engineer battalion, completed the work by the end of April. For Army General Hospital 39 and Army Station Hospital 176, each of 600-bed capacity, the Seabees erected Quonset and wood-frame buildings.
NOB Saipan was disestablished on 30 June 1949.
Tinian, Naval Air Base and Naval Base
With an area of 39-square-miles (101-square-kilometers), Tinian Island (15°01'N, 145°38'E) is the third largest island in the Mariana Islands. The island volcanic rock overlaid with limestone and the highest point is Mount Kastiyu at 558-feet (170-meters) on the southeastern coast.
Tinian lies just southwest of Saipan and is separated from it by a strait only 3-miles (4.8-kilometers) wide; Guam is about 85-miles (137-kilometers) to the southwest. The island is about 12-miles (19-kilometers) long, from north to south, and about 6-miles (9.7-kilometers) wide, with a generally flat and terraced terrain. The Japanese had developed extensive sugar plantations; the island's industry was confined to sugar refining
The northern part of the island contains an extensive plateau ideally suited for a large airdrome, a circumstance that had not been overlooked by the Japanese. During the months just prior to the Marianas offensive, they had done considerable work there on two airstrips, one a coffin-shaped field, 4,700-feet (1,432-meters) long, and another of more orthodox shape, 3,900-feet (1,189-meters) long. In addition, they had completed a 5,000-foot (1,524-meters) strip about midway of the west coast, and had begun a small runway near the center of the island. Japanese construction on the northern plateau formed the nucleus of the great airfields the U.S. built on Tinian during the succeeding months.
Plans for the development of Tinian as a major air base had been carefully laid at Pearl Harbor during the months preceding the invasion, by a nucleus staff of the Seabees in cooperation with Army engineers and the joint staff agencies of the area command. According to the plan adopted, two strips built by the Japanese, the 4,700-foot (1,432-meter) airstrip at the north end of the island (15°04' 20"N, 145°38 18"E) and the 5,000-foot (1,524-meter) runway on the west coast (14°59' 57"N, 145°37' 10"E), were to be extended to 6,000-feet (1,829-meters) each so that medium and heavy bombers could operate from them. After that extension had been made, the northern runway was to be lengthened to 8,500-feet (2,591-meters) and the neighboring Japanese-started strip was to be completed to the same length, to support the opening operations of U.S. Army Air Forces B-29 Superfortresses. The next scheduled step was to be the building of two more 8,500-foot (2,591-meter) strips on a new site in the vicinity of the west coast strip. In addition, a field, having a 6,000-foot (1,829-meter) runway, for Navy use, to be designated East Field, was to be built at a location to be determined on the scene.
The invasion of Tinian was principally a shore-to-shore operation from Saipan by landing craft. On 24 July 1944, the 4th Marine Division landed on two narrow beaches on the northwest coast of the island. Facing them were 5,050 Japanese Army and 4,100 Japanese Navy troops. A few days after the initial assault, the surviving defenders fled to a network of caves in the hills and cliffs of the island and on 1 August the island was declared secured.
On 27 July, the Seabees began the repair of the 4,700-foot (1,432-meter) Japanese airstrip in the north at Ushi Point, filling bomb and shell craters with swept-up shrapnel fragments. By evening, a strip, 150-by-2,500 feet (46-by-782-meters), had been repaired. The next day, the first plane landed. At the end of two days the field had been repaired for its full length, and on the third day, the Seabees widened it to 200-feet (61-meters). Air transports immediately began operating from the field, bringing in supplies and evacuating wounded.
The rehabilitated northern strip was extended by 1,000-feet (305-meters) at its west end and 650-feet (198-meters) at the east end and was widened to 300-feet (91-meters). This strip formed the first element of what later was to become the great North Field (15°04' 20"N, 145°38 18"E). The second task, undertaken in September, was the completion to a 6,000-foot (1,829-meter) length of the neighboring Japanese-started strip; thereupon, designated North Field, Strip No. 3. The existing Japanese field on the west coast of the island, which had been severely damaged during the assault period, was then reconditioned to serve as a 4,000-foot (1,219-feet) fighter strip.
During this early period, Navy PV-1 Venturas and PB4Y-1 Liberators and Marine TBM-1C Avengers operated from the North Field runways. When the time arrived for enlarging those strips to permit their use by Superfortresses, it was necessary first to provide a new field for the Navy's use. A site, 1-mile (1.6-kilometers) east of the west coast fighter strip, was chosen, adjoining the area selected for the proposed third and fourth B-29 strips; construction of a new 6,000-foot (1,820-meter) runway, designated West Field, Strip No. 3, was put under way. The East Field site, originally planned for the Navy field, was rejected as unsuitable for proper development. To expedite the construction of the Navy strip, on 1 October practically all construction at North Field was brought to a halt and all the heavy-duty earth-moving equipment on Tinian was moved to West Field. By 15 November, the strip was complete, and the entire Navy air force moved to its new base and Naval Air Base Tinian was established on 20
November. Accessories to this strip included 16,000-feet (4,877-meters) of taxiway, 70 hardstands, 345 Quonset huts, 33 buildings for repair and maintenance facilities, seven magazines, and a 75-foot (23-meter) high control tower. By 28 December, there were four B-29 groups at North Field. They flew their first training mission on 21 January 1945 bombing the airfield in Truk Atoll in the Caroline Islands. Their first mission to Japan was flown on 4 February when they bombed the urban area at Kobe, Japan.
After the completion of the Navy air facilities at West Field, attention was directed again to North Field and to the extension and strengthening of the two 6,000-foot (1,829-meter) bomber strips to fit them for B-29 use. At the same time, the scope of the plan for North Field was enlarged, calling for four B-29 strips instead of two.
The North Field project was assigned to the Seabees, when, in turn, divided it into several phases and assigned principal responsibility for each phase was assigned to each Seabee unit.
The first phase was the development of Strip No. 1, to its required length of 8,500-feet (2,591-meters) and width of 30-feet (9.1-meters), and the construction of taxiways, hardstands, and aprons necessary to serve it. Strip No. 1 was completed nine days ahead of the date set and the first B-29 landed on 22 December.
The next phase was the construction of a strip, designated as North Field No. 2, between the two earlier strips, including taxiways, hardstands, and a service apron for a projected fourth strip. Strip No. 2 was completed and received its first long-range bomber on 27 February 1945. Instead of proceeding immediately with construction of Strip No. 4, all construction effort was then directed to the development of the long-range bomber strips planned for West Field.
Construction of West Field, Strip No. 1, the first B-29 strip at that location, north of the Navy's West Field strip (No. 3), had been begun on 1 February 1. Construction of two 8,500-foot (2,591-meter) strips proceeded simultaneously. Both strips, laid out parallel to each other, were 500-feet (152-meters) wide and included 53,000-feet (16,154-meters) of taxiway, 220 hardstands, two service aprons, sub-service aprons, and warm-up aprons, 251 buildings for administration, repair, and maintenance, and four personnel camps. On 2 April, Strip No. 1 received its first B-29 and Strip No. 2 was completed on 20 April. By 7 April, there were four groups of B-29s at West Field and they flew their first mission on 5 May bombing the industrial area at Kure, Japan. When completed, West Field had two 8,500-foot (2,591-meter) and a 6,000–foot (1,829-meter) runways.
After West Field was finished, the Seabees took up its unfinished work at North Field. The fourth 8,500-foot (2,591-meter) strip was constructed to a width of 500-feet (152-meters). In addition, the other three strips were widened to 500-feet (152-meters) and additional hardstands were built. On 5 May 1945, North Field, Strip No. 4 was complete.
Total facilities at North Field, in addition to the four 8,500-foot (2,591-meter) runways, comprised eight taxiways, aggregating nearly 11-miles (18-kilometers), 265 hardstands, two service aprons, 173 Quonset huts, and 92 steel arch-rib buildings. The four runways were parallel 1,600-feet (488-meters) apart, with taxiways in the intervening spaces. Construction of the field would have been simpler if the runways had been only 7,000-feet (2,134-meters) long, the width of the Tinian plateau. The last 1,500-feet (458-meters) spilled over the edge of the plateau, and extensive fills had to be made on both the east and the west sides of the island. Moreover, after construction work had started the maximum permissible taxiway grade was reduced from two and one-half to one and one-half per cent, because of an operational decision to taxi the planes under their own power to take-off line, instead of towing them by tractor as originally planned. This change increased the amount of earth to be moved at North Field by 500,000 cubic-yards (382,277 cubic-meters).
On 6 and 9 August 1945, B-29s from North Field dropped atomic bombs on Hiroshima and Nagasaki, Japan which ended World War II.
The construction of the Tinian fields represented a gigantic earth-moving operation. Deep cuts in hard coral and high fills characterized the work at both North Field and West Field. Cuts as deep as 15-feet (4.6-meters) and fills as high as 42-feet (13-meters) had to be made. North Field excavations totaled 2,109,800 cubic-yards (1,613,058 cubic-meters), and the amount of fill required was 4,789,400 cubic-yards (3,661,759 cubic-meters). At West Field the quantities of cut and fill were 1,718,050 cubic-yards (1,313,543 cubic-meters) and 3,298,490 cubic-yards (2,521,877 cubic-meters), respectively. The great volume of excess fill necessitated development of huge borrow pits in the coral underlying the island.
Tank-farm construction was started in early September 1944. On 3 November, after the construction of 25,000-barrel storage capacity. By 27 November, a submarine pipeline and 56,000-barrel storage space were ready for use by the first tanker. The entire project was completed by 8 March 1945.
The island fuel system, as completed, consisted of a single 14,000-barrel storage farm for diesel oil, one 20,000-barrel farm for motor gasoline, and a series of six farms, with capacity of 165,000 barrels, for storage of aviation gasoline. All fuel was brought ashore through the submarine pipeline, from a single tanker mooring just north of Tinian Harbor. Numerous pumping stations and 86,000-feet (26,213-meters) of main pipeline distributed fuel over the island. The diesel-oil and motor-gasoline farms were located close enough to the tanker mooring to be filled from the tanker's pumps. Each was fed by a 6-inch (15-centimeter) line which permitted a filling rate of 700 to 800 barrels per hour. The aviation-gasoline storage was divided into two main farms and four secondary farms located near the two airfields. The system had six dispensing points for North Field and two for West Field.
In the selection of Tinian as a B-29 base, because of its potentialities for development as a large airfield, consideration had to be given to the absence of any natural harbor. The only site on the island that was conceivable for a harbor was at Tinian Town, where the southwest side of the island formed a slight bay in which it was possible to anchor five or six ships at one time.
Waterfront construction was divided into two phases. The first phase lasted from D-Day until the middle of November, when all effort was directed to building and maintaining temporary facilities. When the island was secured, the Seabees found themselves in possession of two small beaches capable of accommodating landing craft, a pontoon pier constructed by the assault forces, and two badly damaged Japanese masonry piers.
In August, two temporary marine railways for use in repairs to landing craft, mechanized (LCM) and landing craft, vehicle and personnel (LCVP) were built. A section base was started about 1-mile (1.6-kilometers) south of Tinian Town, but was abandoned because the location was too unprotected. A severe storm in early October destroyed the two railways, the existing work at the section base, the pontoon pier, and one of the masonry piers. To alleviate the critical situation resulting from this damage, a pontoon pier was constructed of three sections of 4-by-30-foot (1.2-by-9.1-meter) strings, connected by flexible bridges which enabled the pier to withstand the shock of rough water.
The second phase covered the period subsequent to the middle of November and involved the construction of permanent harbor facilities. The major project for this period was the provision for berthing eight Liberty ships.
When U.S. troops took Tinian, the construction forces inherited a network of roads that became the fabric of the island's road system. The general layout of the existing roads and the similarity in shape of Tinian to Manhattan Island resulted in the naming of the roads after the streets of New York.
The Japanese-built roads were too narrow for U.S. heavy traffic, were poorly drained, and had no shoulders. Heavy trucks slid into the ditches and tracked a slippery coating of mud upon the road surface in climbing back.
The first problem was the maintenance of the 35-miles (56-kilometers) of existing roads, with the limited equipment which could be spared from high-priority airfield construction. The Japanese roads were resurfaced with 8-inches (20-centimeters) of pit-run coral, and the necessary shoulders and drainage were provided. Rainy seasons and dry seasons produced conflicting road maintenance problems. In dry weather, the roads became dusty and rough, and a continuous wetting-down with salt water was necessary. It was found advantageous to mix clay with the coral surface during this season. During the rainy season, the roads had to be bladed to the center after each rain in order to be kept passable.
As equipment became available, new road construction was pushed to the utmost. Tinian consists of several plateaus of different heights, and road construction required a great deal of blasting in order to keep the grades down for heavy-truck traffic. The roads were built 22-feet (6.7-meters) wide, with 3-foot (91-centimeter) shoulders and ditches to carry off heavy rainfall. Major roads were surfaced to 30-feet (9.1-meters) in width to support heavy traffic. About 34-miles (55-kilometers) of new roads were constructed on the island. To solve the problem of rapidly increasing traffic on the two main north-south roads, a second 22-foot (6.7-meter) lane was constructed parallel to each road to provide dual highways.
Necessity for camp construction was considered to be of secondary importance to the completion of military installations on Tinian, once a unit had standard minimum facilities. Camps were divided into two main classes: temporary camps, of framed tents with wooden decks and screened sides, and semi-permanent camps with Quonset huts for Navy and aviation personnel and prefabricated wooden barracks for Army personnel. Both types of semi-permanent buildings were allocated on the basis of 20 enlisted men or eight officers per building.
Another problem was the building of mess halls and similar facilities for large units, with only 20-by-56-foot (6.1-by-17-meter) Quonsets supplied. The development of housing on Tinian involved camps for more than 12,000 Seabees, 13,000 other naval personnel, and 21,500 Army personnel.
The first medical facility on Tinian, a 100-bed tent hospital, was completed in September 1944. This served as the only hospital on the island for military personnel until the completion of the 600-bed Navy Base Hospital 19, in early December. Quonset huts, modified where required to suit operational needs, were used. Rearrangement of floor space increased the capacity to 1,000 beds. A 600-bed hospital of similar design was completed for the Army in March 1945. A 1,000-bed hospital was made available in June, with the reconversion of the camp area vacated by the Seabees, which moved to Okinawa. On V-J Day, construction was nearing completion on a 4,000-bed hospital on the South Plateau.
General supply facilities for Tinian were of three types: those for the garrison forces; those for general Navy supply activities; and those for the Seabees, which handled construction supplies.
In early August 1944, the Seabees were assigned the layout and construction of the Seventh Field Depot for the Marines. The project, which included camp facilities for a Marine quartermaster battalion and the improvement of 300,000 square-feet (27,871 square-meters) of open storage space, was completed early in November. In December, the Seabees began the reconstruction and expansion of the depot, then designated as the quartermaster depot of the Army garrison forces. The completed depot consisted of three camps, 386,000 square-feet (35,861 square-meters) of warehouse storage, 2 million square-feet (185,806 square-meters) of surfaced open storage, and about 63,000 cubic-feet (1,784 cubic-meters) of refrigerated storage.
In September 1944, the first ammunition storage dump of 11 revetments was constructed. Access roads were developed on the basis of existing roads. Expansion of this facility to include 254 coral-surfaced revetments, 25-by-75-feet (7.6-by-23-meters), and almost 14-miles (23-kilometers) of main and secondary roads, undertaken in November 1944, was completed in February 1945.
On 28 January 1945, work was started on an additional bomb dump of 20,000-ton (18,144-metric-tonne) capacity, in an area near West Field. Work progressed slowly because of limited equipment; the 468 revetments were not finished until early summer of 1945.
In February 1945, the Seabees met a three-week deadline in the construction of an aerial mine assembly and storage depot. The project involved the construction of two 40-by-200-foot (12-by-61-meter) Quonset huts with concrete decks, surrounded by a 12-foot (3.7-meter) earth revetment on three sides; two 20-by-50-foot (6.1-by-15-meter) Quonset magazines with concrete decks and an earth cover; twelve 30-by-40-foot (9.1-by-12-meter) ready storage revetments; and about one miles of 20-foot (6.1-meter), coral roadway.
Tinian, though it contains not a single stream and has only one small fresh-water lake, is an island rich in water. The average yearly rainfall is in excess of 100-inches (2.54-meters), and the porous coraline structure of the island permits the rain water to filter into the ground with very little runoff. The Japanese had developed a well-and-reservoir system, with the necessary pipelines to serve the Tinian Town area.
After the island was secured, the Seabees assumed the development and control of the water supply. Purification units were set up at four small shallow wells in the Marpo region, where the water was filtered and chlorinated. These wells, in addition to Hagoi Lake, provided sufficient water, with rationing.
The Seabees rehabilitated and extended the existing Japanese pipeline from the reservoir. Well drilling was undertaken, and, and the water system was eventually composed of 17 deep wells. Marpo well, Tinian Town well, and Hagoi Lake, providing 20-U.S. gallons (17 Imperial gallons or 76 liters) of water, per man, daily. With the increased development of water sources during August, it was no longer necessary to ration water.
The water supply eventually included a skimming trench in Marpo Valley, designed to produce 1.8 million U.S. gallons (1.5 Imperial gallons or 6.8 megaliters) per day. The service group camps and shops at north Field were supplied from two wells in that vicinity. The island system was designed for 30 U.S. gallons (25 Imperial gallons or 114 liters) per man per day.
To provide drinking water, food, clothing, and shelter for the civilians held in custody at Camp Churo, reliance was placed on what facilities the Japanese had left.
Using Japanese 4-by-4-inch (10-by-10-centimeter) timber taken from damaged farm and village buildings, the Seabees supervised the native laborers in the construction of tarpaulin shelters for initial housing. As more materials were brought in by salvage crews, the tarpaulin shelters were replaced by wood-frame and corrugated-iron roofed sheds.
A 100-bed civilian hospital, constructed largely of salvaged material, was completed in September 1944. A 100-bed Quonset-hut hospital replaced this initial hospital in April 1945.
Captured Japanese civilians, who knew the location of food supplies, were assigned to food salvage details. The existing food supply was supplemented by American food and by extensive agricultural development. When firewood supplies on the island showed signs of exhaustion, the Seabees improvised a diesel-oil stove for cooking, using cement and salvaged fire-brick, with burners made of salvaged scrap pipe and tubing.
Naval Air Base Tinian was disestablished on 1 December 1946 and Naval Base Tinian was disestablished on 1 June 1947.