3 of 8 Tinian

Where the two journeys meet

Tinian

Tinian is a small, mostly flat island in the Northern Mariana Islands. US Marines captured it in the summer of 1944, and Navy Seabees turned its northern end into the largest airfield in the world. In the summer of 1945 the two journeys met here. Project Alberta assembled the bombs, and the 509th Composite Group flew them to Japan. 1 2 3

The island

Tinian covers about 101 square kilometres (39 square miles) and is about 12 miles long. It lies 3 miles south-west of Saipan. 1 2 12

Its Chamorro people were forced to move to Guam under Spanish rule, between about 1695 and 1720. Spain sold the Northern Marianas to Germany in 1899. Japan took them in 1914 and governed them after the First World War under a League of Nations mandate. 2 4 13 14

From 1926 a Japanese company, Nan’yo Kohatsu, grew sugar cane over about 90 per cent of the island, served by about 40 miles of narrow gauge railway. When the Americans landed, about 15,700 civilians lived on Tinian. Most were Japanese and Okinawan, and about 2,700 were Korean. 1 4 5 14

The battle

Landing at Tinian Town in the south, against prepared defences, was judged too costly. So on 24 July 1944, while the 2nd Marine Division staged a feint off Tinian Town, the 4th Marine Division landed on two tiny beaches on the north-west coast. White 1 was about 60 yards wide and White 2 about 160 yards. 4 5

The 2nd Marine Division followed on 25 July. US aircraft dropped napalm, one of its first uses in combat. The island was declared secure on 1 August 1944. 4 5 15

More than 5,000 Japanese dead were counted and buried, and only about 250 to 400 soldiers were taken prisoner. The United States lost 389 killed and 1,816 wounded. 4 5 15

Many civilians died. Some were caught in the fighting, some were killed by Japanese soldiers, and some took their own lives at the cliffs at the southern end of the island. Estimates of the civilian dead range from hundreds to about 4,000. 2 4 5 14

About 13,000 civilians were held in Camp Churo by 10 August 1944. Many died of disease and hunger in the first months, and the survivors were sent home in 1946. 4 5 14

North Field

Aerial view of North Field, Tinian, in 1994, its long runways cut through the scrub.
North Field from the air in 1994. Cdr. Dana R. Potts, US Navy (DN-ST-95-01291), Public domain (US government), source

The Navy’s Seabees began repairing the Japanese airstrip at Ushi Point on 27 July 1944, while the fighting went on. About 15,000 Seabees worked on the island. 1 5 6

North Field had four parallel runways, each 8,500 feet long and 1,600 feet apart, with hardstands for 265 B-29s. Building them moved about 11 million cubic yards of coral. 1 6

The first B-29 landed at North Field on 22 December 1944. The 313th Bombardment Wing flew from North Field, and the 58th from West Field on the other side of the island. 1 4 6

Tinian’s shape reminded the builders of Manhattan, so they named its roads after New York streets: Broadway, Eighth Avenue, 42nd Street, Riverside Drive. Many of the names are still in use. 1 6 16

North Field, Tinian, in 1945 Four long runways run east to west, one above the other. The top one is Runway Able. Above it is the 509th Composite Group's apron with two loading pits. To the upper left is the site of the bomb assembly buildings. To the lower right, below the runways, is the 509th's camp. An arrow shows north at the top. Runway Able four runways, each 8,500 ft 509th apron, two pits Assembly buildings 509th camp N
North Field in 1945, simplified. Not to scale, and the places are shown only roughly where they were. The 509th’s apron and loading pits lay north of Runway Able, the northernmost runway; the bomb assembly buildings stood to the north west, and the 509th’s camp to the south east.

The 509th and Project Alberta

The 509th Composite Group began arriving at North Field in May 1945. It lived in a former Seabee camp, and its technical area and loading apron lay north of Runway Able, set apart from the rest of the airfield. 1 2 7

From April 1945 the Seabees built three air-conditioned buildings to assemble the bombs, four more for the fusing, detonator, pit and observation teams, seven warehouse-type buildings and ten magazines. Fifty-one people from Project Alberta came out from Los Alamos to do the work. 2 3 17 18

Little Boy was prepared in Assembly Building No. 1 and Fat Man in Assembly Building No. 2. 19 20

The 509th’s aircraft were kept in a guarded corner of the base, and access was tightly restricted. The group flew few raids, and the other airmen on Tinian mocked it, even stoning its camp. 7 11

The loading pits

The bombs were too large to wheel under a B-29, so two pits with hydraulic lifts were dug on the 509th’s apron. A third was built on Iwo Jima, in case a bomber had to land there. 2 3 7

Each bomb was towed to a pit on a trailer and lowered in on the lift. The B-29 was edged backwards over the pit, and the bomb was raised into its bomb bay. 7 19

Little Boy was loaded into Enola Gay on the afternoon of 5 August 1945, and Fat Man into Bockscar on the evening of 8 August 1945. 3 8 9 10

A glass-roofed shelter over one of the atomic bomb loading pits on Tinian, with a plaque in front.
One of the bomb loading pits on Tinian under its glass cover, 2011. kajikawa, CC BY 3.0, source

Then

August 1945

Two open pits on a guarded apron, each with a hydraulic lift, used to load the two bombs. 3 19

Now

Today

After the war the pits were filled with earth and landscaped, each with a bronze plaque. They were dug out again in the 2000s, in an effort led by Tinian’s historian Don Farrell, and now sit under glass. 1 2 7 21

The plaques name Pit No. 1 for Little Boy and Pit No. 2 for Fat Man. Other accounts, including the Marianas Visitors Authority’s, say both bombs were loaded from the same pit. 8 12

Leaving Tinian

Most of Project Alberta’s scientists and technicians left Tinian on 7 September 1945. The 509th sailed on 17 October 1945 aboard the transport Deuel, and reached Oakland on 5 November. 3 11

Tinian today

Tinian is part of the Commonwealth of the Northern Mariana Islands, a US commonwealth. Most people live in San Jose, once Tinian Town. The 2020 census counted 2,044 people on the island. 1 22 23

North Field was named a National Historic Landmark in 1985. Under a 1983 lease the US military uses the northern two thirds of the island, and North Field can close during training. 1 22

Visitors can drive Runway Able and see the glass-covered loading pits, the Japanese air operations buildings and the landing beaches. Memorials stand at the southern cliffs. Tinian is reached by a short flight from Saipan. 1 12 16 24

Sources for this page24
  1. Jackson-Retondo and Johnson, US National Park Service, for the Advisory Council on Historic Preservation, Tinian Landing Beaches, Ushi Point Field, and North Field National Historic Landmark: Section 213 Report. Checked 11 October 2026.
  2. US National Park Service, Tinian Island during the Manhattan Project. Checked 11 October 2026.
  3. US Department of Energy, Office of Scientific and Technical Information, Tinian Island. Checked 11 October 2026.
  4. Major Carl W. Hoffman, US Marine Corps Historical Division, 1951, reproduced by HyperWar, The Seizure of Tinian. Checked 11 October 2026.
  5. US National Park Service, American Memorial Park, Battle of Tinian. Checked 11 October 2026.
  6. US Navy Bureau of Yards and Docks, 1947, reproduced by HyperWar, Building the Navy's Bases in World War II, volume II, chapter XXVIII. Checked 11 October 2026.
  7. US National Park Service, 1985, National Register nomination 85003268: Tinian Landing Beaches, Ushi Point Field and North Field. Checked 11 October 2026.
  8. US National Park Service, Photographs filed with National Register nomination 85003268 (E. Thompson, April 1983). Checked 11 October 2026.
  9. Air and Space Forces Magazine, Near Failure at Nagasaki. Checked 11 October 2026.
  10. US Department of Energy, Office of Scientific and Technical Information, Assembling Fat Man. Checked 11 October 2026.
  11. Atomic Heritage Foundation, 509th Composite Group. Checked 11 October 2026.
  12. Marianas Visitors Authority, Tinian. Checked 11 October 2026.
  13. Francis X. Hezel, Micronesian Seminar, 1988, From Conquest to Colonization: Spain in the Marianas, 1690 to 1740. Checked 11 October 2026.
  14. Boyd Dixon and others, Pacific Asia Inquiry, volume 12, University of Guam, Archaeological Survey of WWII Remains at Laderan Kastiyu, Tinian. Checked 11 October 2026.
  15. Richard Harwood, US Marine Corps, World War II commemorative series, reproduced by NPS History, A Close Encounter: The Marine Landing on Tinian. Checked 11 October 2026.
  16. US Navy, June 2026, CNMI Joint Military Training Final Environmental Impact Statement, chapter 3, transportation. Checked 11 October 2026.
  17. David Hawkins, Los Alamos Scientific Laboratory, written 1946 to 1947; via the US Department of Energy, OSTI, Manhattan District History, Project Y, the Los Alamos Project, Vol. I (LAMS-2532), chapter XIX, Project Alberta. Checked 14 October 2026.
  18. Atomic Heritage Foundation, Project Alberta. Checked 11 October 2026.
  19. US National Archives, Photographs of Atomic Bomb Preparations at Tinian Island (series 77-BT, NAID 519392). Checked 11 October 2026.
  20. Pacific Coastal Research and Planning for the Northern Marianas Humanities Council, with the CNMI Historic Preservation Office, 2023, Tinian's World War II heritage (story map). Checked 11 October 2026.
  21. Brad Lendon, CNN, 2020, Hiroshima after 75 years: Walking the path of the atomic bomb. Checked 11 October 2026.
  22. US Navy, June 2026, CNMI Joint Military Training Final Environmental Impact Statement, chapter 3, land use. Checked 11 October 2026.
  23. US Census Bureau, 2020 Census, Commonwealth of the Northern Mariana Islands, table 1. Checked 11 October 2026.
  24. US National Park Service, Tinian Landing Beaches, Ushi Point, and North Fields, Tinian Island. Checked 11 October 2026.
Where sources differ10
  • The Navy's 1947 history gives 22 December 1944 for the first B-29 at North Field. A later Navy Seabee history gives 21 December.
  • The National Register nomination dates the 509th's first arrivals to 19 May 1945. Its ground echelon's ship reached Tinian on 29 May.
  • The Department of Energy history says Little Boy was loaded in the early afternoon of 5 August. The plaque at the pit says late in the afternoon.
  • Modern surveys give Tinian's area as 39 square miles. The Marine Corps history of 1951 and one National Park Service page give about 50.
  • The National Park Service dates the removal of Tinian's Chamorro people to Guam to 1720. The historian Francis Hezel dates it to about 1695.
  • US deaths on Tinian are given as 389 including Navy losses (Marine Corps history), 368 and 355 (two National Park Service pages). Estimates of the Japanese garrison run from about 6,200 to over 9,000, and of prisoners from 252 to 404.
  • The Marine Corps history gives both about 13,000 civilians held by 10 August 1944 and, elsewhere, more than 9,000.
  • The Atomic Heritage Foundation gives North Field space for 269 B-29s. Two National Park Service pages say six runways, which counts West Field's two as well.
  • The Department of Energy history lists three air-conditioned assembly buildings. The Atomic Heritage Foundation mentions one. The Department of Energy gives the four other buildings to the fusing, detonator, pit and observation teams; the official Los Alamos history says only that all the laboratory and instrument work was done in them.
  • No official source gives the year the pits were reopened. The glass covers were in place by May 2010.

Checked against its sources on 11 October 2026.