USS Indianapolis (CA-35)

USS Indianapolis was one of two Portland-class heavy cruisers, commissioned on 15 November 1932. Built under the 10,000 t / 8-inch limits of the Washington Treaty, she displaced about 9,950 t standard and 12,750 t at full load, ran 186 m long on a 20.1 m beam, and carried a main battery of nine 203 mm (8-inch) /55 guns in three triple turrets.

Fast, handsome and well-equipped as a flagship, she spent the 1930s as a showpiece — carrying President Franklin Roosevelt on goodwill cruises — before becoming, in the Pacific War, the flagship of Admiral Raymond Spruance’s Fifth Fleet. From that role she would steam through nearly every major central-Pacific campaign of 1943–1945.

Indianapolis was built for speed and gun power rather than protection. Her 4 Parsons geared turbines, fed by 8 White-Forster boilers and developing about 107,000 shp on four shafts, drove her at 32.5 knots, with a cruising radius of roughly 10,000 nmi at 15 knots. Like all treaty cruisers her armour was modest: a belt of around 127 mm (5 in), a deck of 57–65 mm, and turret faces of about 65 mm.

Her nine 203 mm /55 rifles fired a 118 kg armour-piercing shell to over 27 km, backed by eight 127 mm (5-inch) /25 dual-purpose guns and, by 1945, a heavy automatic AA battery of 40 mm Bofors and 20 mm Oerlikon mounts added through the long Pacific campaign. Her great vulnerability — common to her type — was the absence of strong underwater protection against torpedoes.

As Fifth Fleet flagship, Indianapolis was at the centre of the American drive across the Pacific. Her 203 mm guns bombarded Japanese positions during the assaults on the Gilberts, Marshalls, Marianas and the Western Carolines, and she screened the carriers through the great carrier battles of 1944. She earned ten battle stars for her wartime service.

Off Okinawa on 31 March 1945 she was struck by a kamikaze; the aircraft and its bomb tore through the ship and out the bottom, killing nine men and forcing her back to Mare Island in California for major repairs. It was while completing those repairs that she was chosen for the most secret mission of the war.

In July 1945 Indianapolis was given a top-secret cargo and ordered to make best speed across the Pacific. She carried the uranium and key components of “Little Boy” — the atomic bomb that would be dropped on Hiroshima. Steaming at high speed, she covered the ~5,000 nautical miles from San Francisco to the island of Tinian in only ten days, delivering her cargo on 26 July 1945.

Her mission accomplished, she was routed onward, unescorted, toward Leyte in the Philippines. The decision to send a cruiser without anti-submarine escort across waters where Japanese submarines still operated would have catastrophic consequences.

Shortly after midnight on 30 July 1945, the Japanese submarine I-58, under Lieutenant Commander Mochitsura Hashimoto, fired a spread of torpedoes; two struck Indianapolis on the starboard bow. The hits blew off part of her bow and knocked out her power, and — unable to signal effectively or steer — she rolled over and sank in about 12 minutes.

Of roughly 1,195 men aboard, around 300 went down with the ship. Some 890 were left alive in the open sea, most in kapok life jackets, with few rafts, little water and no shelter. They did not yet know that the greater ordeal lay ahead of them — not in the sinking, but in the days that would follow it.

Because of a chain of communication failures, the ship was not missed for nearly four days. No distress signal was acted upon, and the Navy’s tracking system did not register that she had failed to reach Leyte. The survivors drifted under the tropical sun, tormented by thirst, exposure and salt-water sores — and by repeated shark attacks, as oceanic whitetips worked among the helpless clusters of men, day after day.

They were found only by chance, when a patrol plane on an unrelated flight spotted the oil slick and the men in the water on 2 August. The pilot of a rescue flying boat, Adrian Marks, disobeyed standing orders to land in the open sea and began pulling survivors aboard, lashing some to his wings. By the time the ships arrived, only 316 of the roughly 890 were still alive. The loss of nearly 880 men was, and remains, the worst single loss of life at sea in US Navy history.

USS Indianapolis embodies the extremes of the Pacific war in a single hull. For thirteen years she was a fast, powerful flagship — nine 203 mm guns, 32.5 knots, ten battle stars — at the very heart of the American offensive, and she carried the weapon that ended the war. Days later she became the scene of one of its worst disasters.

Her captain, Charles B. McVay III, survived — and was then court-martialled for hazarding his ship by failing to zigzag, the only US Navy captain ever tried for losing his ship to enemy action, even though the Japanese commander Hashimoto testified that zigzagging would have made no difference. McVay was convicted; the injustice haunted him until his death in 1968, and only in 2000 did the US Congress formally exonerate him. The wreck itself lay undiscovered until 2017, more than 5,500 m down on the Pacific floor.

• Roger Chesneau (ed.), Conway’s All the World’s Fighting Ships 1922–1946 (Conway Maritime Press).
• Doug Stanton, In Harm’s Way: The Sinking of the USS Indianapolis (Henry Holt).
• Norman Friedman, U.S. Cruisers: An Illustrated Design History (Naval Institute Press).
• Lynn Vincent & Sara Vladic, Indianapolis: The True Story of the Worst Sea Disaster in U.S. Naval History (Simon & Schuster, 2018).