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Editor’s note: This page has been extracted from the 112th Seabees article Tinian in WWII – Teamwork and Effort (2003) with permission of the 112th Seabees. Pictures, historically significant sub-chapter titles, highlight text and links have been added to complement the authors’ writing.

Tinian Island Capture and Construction

Written by Edwin E. Foster, 112th NCB (Seabees) Historian

In collaboration with
Phm2C Lewis E Foster 112th NCB (Seabees), Tinian 1944-45 /
Tinian vets of 112th NCB     

Immediately following the capture of Tinian Island in July 1944, 1500 Navy Seabees constructed the world’s largest and war’s most important air base in record time. In what became known as the “Miracle of Construction”, battalion runway builders hauled, blasted and packed down enough coral to fill three times the volume of Hoover Dam in six 8500 foot runways allowing the arrival of B-29’s and commencement of the decisive bombing operations to begin that October.

Tinian is a tiny 39 square mile coral island in the Northern Marianas Islands that rests atop the seven mile deep Marianas Trench.  Tinian  became  the  largest  and  most valuable airbase of World War II while the United States and the Empire  of  Japan  were locked  in  mortal  combat.  Beginning  in  late  1944,  two  complete  airfields, North  Field and West Field, were efficiently constructed in  record  time  from  the  island’s  plentiful coral deposits. A vast and confident fleet of long–range B-29 “Superfortresses” soon arrived from the China-Burma-India Theater and directly from the United States. Shortly thereafter, Tinian based B-29s launched from the newly constructed and expansive 8500+ feet long runways, besieged the Japanese home islands on a continuous 24 hour basis. Many incredible feats in construction, logistics, teamwork and air-warfare were witnessed on and from this tiny coral island. Paramount was Tinian’s contribution to the Manhattan Project that culminated in two atomic bomb missions that hastened the end of World War II and clinched Tinian’s deserved place in history.

Battle of the Philippine Sea – The Great Marianas Turkey Shoot

Great Marianas Turkey Shoot

Both the Japanese and the Americans realized the strategic importance of air bases at Saipan, Tinian, and Guam in the Central Pacific in mid-1944. The U. S. invasion of the Marianas Islands on 15 June 1944 brought the Japanese Navy out fighting for the first time since the naval battles of Guadalcanal in the fall of 1942. Determined to force a showdown battle, Admiral Soemu Toyoda ordered a combined fleet of 9 carriers and 18 battleships and cruisers to attack the U.S. warships protecting the landing on Saipan.  There  Admiral Raymond Spruance, Commander of the U. S. Fifth Fleet (14 battleships,  25 carriers and carrier escorts, 26 cruisers, 144 destroyers and countless transports), organized defensive  preparations  and  sent  15  fast  carriers  of  Task  Force 58, commanded by Vice Admiral Marc A. Mitscher, west to intercept the Japanese, then only 90 miles away.

The Battle of the Philippine Sea commenced early  on  19  June  1944  with  an  attack  on  Task Force 58 by Japanese land-based planes from  Guam and Truk. Hellcat fighters from US carriers destroyed 35 enemy fighters and bombers.  The remainder of the battle was fought by 430 Japanese carrier planes attacking the 450 planes of Task Force 58 in four fierce waves. At the end of the eight-hour onslaught, only 100 of the enemy planes returned to their carriers. The rest had been destroyed in the most decisive aerial combat victory in the history of aviation. Thirty American planes were lost in what the American Fliers called the “Marianas Turkey Shoot.”  Incredibly, no damage was done to the U. S. Navy Fifth Fleet’s ships. By 9 July 1944 at a cost of 2,949 Americans killed and 10,364 wounded, Saipan had fallen. The Japanese fared  much  worse  with  24,000  dead from burial count, 3,612 missing, 1,780 prisoners and the Japanese commander of the Pearl Harbor attack, Admiral Nagumo killed. 

Capture of Tinian

Saipan was the staging area for the attack on Tinian 24 July 1944. Task Force Five One, commanded by Rear Admiral Harry W. Hill, along with the 2nd and 4th Marine Divisions commanded by Major General Roy S. Geiger, teamed up to invade the island of Tinian which is only three and a half miles distant from Saipan. Defending the island were 9,162 Japanese troops. The invasion of Tinian hinged on a fake landing on the southern part of the island near Tinian Town. Supported by shore bombardment from the USS Colorado (which received 22 damaging hits from Japanese shore batteries), the 2nd Marine Division faked an invasion by lowering landing craft and men into the water. Simultaneously, the 4th Marine Division was launching an all-out invasion at White Beach on the northwest side of the coral island. The marines efficiently overcame the numerically superior Japanese force on 1 August in what is considered to be the best-executed amphibious operation of the war. Marine casualties were 328 dead and 1,571 wounded. The entire Japanese garrison was destroyed and as previously witnessed on Saipan, many remaining Japanese chose suicide instead of surrender by jumping   off nearby cliffs.


Seabee Doodlebug

Tinian’s history is forever intertwined with the  culmination  of the  atomic  ”Manhattan  Project” and the infamous U.S.S. Indianapolis tragedy but in the annals of war, the tiny  island  holds other, lesser-known distinctions. At the request of Marines who would soon invade Tinian, the SeaBees removed steel members from the Japanese sugar mill on Saipan and built ten ramps mounted on AMTRAKs that they called their “doodlebugs.” These ingenious landing ramps allowed the Marines to easily scale the 8-foot cliffs along the landing area at White Beach. General Smith and Admiral Turner were very impressed with the SeaBee handiwork. Needless to say, the Tinian invasion was flawless, and extremely successful. Another first in the history of warfare that later proved so useful to US forces on Okinawa was napalm. As part of the 13- day bombardment preceding the Tinian invasion, napalm successfully cleared the Japanese defenders from the cane fields and also destroyed enemy defenders in Tinian Town.

Tinian was declared “safe” by the 4th Marine Division on 2 August 1944. Or was it? During the night of 30 January 1945 thousands of pounds of TNT exploded near the center of Tinian, jarring and shaking the ground all over the island and waking everyone asleep.  Several GI’s were killed in the terrific explosion that authorities believed to be the result of sabotage by Japanese soldiers still at large.

War Over Japan, Tinian Island 1945 Pacific War

Tinian Island airbase 1945

Seabee Construction of Tinian Base

A tiny and fairly flat coral island 75 miles north of Guam, Tinian became an ideal B-29 “Superfortress” base for the rest of the World War II. As spoils of war go, four captured runways as well as bountiful coral construction resources made the island an outstanding catch. Right behind the Marines, in their Can-Do manner, SeaBees in jungle green fatigues with uplifted tropical baseball caps swarmed over the island expanse of coral and cane fields to carve out the huge airbases necessary for the new B-29s. A short few months later, North Field and West Field combined was the largest airbase in the world, with six vast 8,500+ feet long runways and a total of 19,000 combat missions launched against the Empire of Japan. 

Tinian’s B-29 airport, consisting of North Field and West Field, was larger than any airport anywhere in the world. North Field had about 13 miles of taxiways and runways. West Field was only a fraction smaller.

The rapid and intensive construction effort on Tinian enabled the B-29 onslaught against the Empire of Japan.

Seabee construction of North Field

On this remote coral island, SeaBees of the Sixth Naval Construction Brigade consisting of the 9th, 13th, 18th, 38th, 50th, 67th, 92nd, 107th, 110th, 112th, 121st and the 135th Battalions commanded by Commodore Paul James Halloran, Civil Engineer Corps USN, built the largest airport in the world. Tinian’s B-29 airport, consisting of North Field and West Field, was larger than any airport anywhere in the world. North Field had about 13 miles of taxiways and runways. West Field was only a fraction smaller. Tinian’s runway construction measured from 425 to 500 feet wide with the then unheard of runway lengths of 8500+ feet. 




The Naval Construction Battalion, the fundamental unit of the SeaBee organization, comprised four companies that included the necessary construction skills for doing any job, plus a headquarters company consisting of medical and dental professionals and technicians, administrative personnel, storekeepers, cooks, and similar specialists. The complement of a standard battalion originally was set at 32 officers and 1,073 men, but from time to time the complement varied in number. Twelve complete Battalions as well as specialized Seabee “Specials” and detachments participated in the effort at Tinian in early 1945.

Battalion builders hauled, blasted and packed down enough coral to fill three times the volume of Hoover Dam. Piled on flat ground, this would form a cube 6700+ feet in height.

Coral runway construction

The SeaBees did all the construction on Tinian. No Army Engineers were involved, as were on many of the previous jobs that were done jointly. In what was the largest construction project  that the recently formed (the “SeaBees” were born 5 March 1942)  Naval  Construction  Battalions had ever undertaken up to that time, Battalion builders hauled, blasted and packed down enough coral to fill three times the volume of Hoover Dam. They built six huge B-29 bomber strips, each a mile and one half long and a block wide, along  with miles  of taxi ways with “hardstands” sufficient to park 400+ aircraft. The SeaBees dug and moved eleven million cubic yards of earth and coral on Tinian.  Piled on flat ground, this would form a cube 6700+ feet in height. 












SeaBee equipment was kept busy 20 hours a day while their maintenance  crews  worked  to repair bulldozers, shovels, trucks and other equipment damaged as a result of the rough

Tinian coral pit

construction activity. Sharp and abrasive coral was especially damaging to tires and GI’s shoes.  In typical SeaBee fashion, one innovative construction crew had a Marine tank team fire armor- piercing shells into the side of a hill so dynamite charges could be placed to break up the coral. The 15,000 Seabees on Tinian operated all types of construction equipment including asphalt plants to pave the airstrips. In addition to the airfields, they built Quonset huts and a wide variety of service buildings including the shop in which the atomic bombs were assembled. Every airstrip was completed on time and none required more than 53 days to build. The Seabee’s motto, “We Build, We Fight” and their “Can Do Spirit” distinguished this group as being able to do any kind of work, any place, under any conditions. The effort of the 6th Naval Construction Brigade on Tinian was truly remarkable. 


Tinian is about the same size and shape as Manhattan, and as soon as U.S. forces captured it in August 1944, a system of

Broadway on Tinian, Pacific War. ©Bill Webster. All Rights Reserved

Broadway divided highway

roads in the same grid pattern as Manhattan was created. In order to transport the huge quantities of bombs and supplies up from the port at the southern end of the island, a divided four lane highway appropriately named “Broadway” was built. The GIs gave the roads typical New York names like Broadway, 8th Avenue and 86th Street. The main north-south road, Broadway, runs parallel to the other main north-south road, 8th Avenue. The strange coincidence that Tinian has streets named after streets in Manhattan, New York has no provable connection with the Manhattan Project, although personnel involved in the project were stationed on Tinian. As soon as rudimentary accommodations were prepared, squadrons of B-29s eager to undertake strategic bombing operations against the Japanese home islands began arriving in October and November at Isley Field on Saipan. The first B-29  mission from the Marianas (Saipan) was witnessed on 24 November 1944. Soon, camps on Tinian were  constructed  to house up to 50,000 U.S. troops and 1.2 million pounds of crops were produced, all of which were consumed on the island. By August 1945, a year after construction started, Tinian was the largest airbase in the world at the time, and accommodated nearly 450 B-29s. 

6th Bomb Group living area. © Bill Webster. All Rights Reserved.

During the last two months of 1944, B-29s began operating against Japan from the islands of Saipan and, Guam. Initial bombing missions were flown during the day at high altitude, concentrating on chemical plants, aircraft factories, harbors and arsenals. Gen. Curtis LeMay studied the poor results and instructed the bombers to begin low-level incendiary raids at night. The raids targeted Tokyo and some of Japan’s other major cities, Nagoya, Osaka, and Kobe.

In January of 1945, the 20th Air Force, 313th Bombardment Wing (6th, 9th, 504th, and 505th Bombardment Groups) under the command of Brig. Gen. John H. Davies took over the newly built North Field on Tinian. They took part in a high-altitude daylight raid on Kobe on 4 February 1945. In April and May 1945, West Field, Tinian received the 58th Bombardment Wing, (40th, 444th, 462nd, and 468th Bomb Groups) which had been redeployed from the now-defunct XX Bomb Command in the China-Burma-India (CBI) theatre. Approximately 450 B-29’s could now  be efficiently launched on a mission from Tinian in 70-80 minutes.

On 22 December 1944, the Army Air Force issued orders for mining operations of Japanese  waters to begin on 1 April 1945. After the order was issued, the Navy moved a team of mine experts to Tinian. One month later, the SeaBees had a mine assembly depot completed and in operation on the island.

In late March 1945 the 504th Bomb Group of the 313th Bombardment Wing, operating from the newly carved out facilities built by the SeaBees on Tinian, lead-off this highly specialized mission – the aerial mining of Japanese waters from the dangerous altitude of 5000 feet.  Each B-29 carried 12,000 pounds of half ton and one ton mines to be strategically and accurately placed in Japanese shipping lanes patrolled by Japanese Navy warships. Japanese Navy searchlights and all anti-aircraft weapons were most effective and deadly; much deadlier than their land based counterparts. During a mine run, a B-29 caught in searchlights could take no evasive action  –  they took everything that was thrown at them by the enemy. Many crews were lost in this operation that was described as “Hell”.

By mid-August 1945, B-29’s had dropped more than 12,000 mines mostly in Shimonoseki Strait between Honshu and Kyushu. Eighty percent of Japanese shipping used this route. In less than five months these planes flew 1,528 mine laying sorties. This  campaign  devastated  the  Japanese merchant fleet. The Tinian based B-29’s in this mining operation sank half of all the tonnage losses suffered by the Japanese merchant marine in the entire war! The 20th Air Force operating from Tinian caused the loss of 9 percent of all Japanese ships operating in the war.

Seabee-Airmen Comradery

Not long after the arrival of the B-29’s on Tinian, a very special comradeship developed between Seabees and Airmen. Many SeaBee Battalions would “adopt” an aircraft by officially painting their logo and name on the B-29’s nose. The quality of life for the crew of the plane improved considerably because the SeaBees provided the crew of “their” Superfortress with better Quonset huts, washing machines, better mattresses, ice cream, cold beer and many other comforts of life. The SeaBees in return were personally and proudly represented in the B-29 raids against the Japanese homeland. 

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