The sinking, and the disaster that followed, caused the greatest loss of life in the history of the United States Navy. It occurred on the night of July 29-30, 1945, seventy-five years ago this month right at the end of World War II.
The ship was a heavy cruiser, the middle size in the three types of warships existing at the time: battleships, cruisers and then destroyers. It was armed with 10 8” guns each of which could fire a 256 lb. projectile a maximum of about thirteen miles. The ship weighed about 10,000 tons and its top speed was about 35 miles an hour.
Under top secret orders, Indianapolis carried the main components for the atomic bomb to the island of Tinian in the Marianas which was then dropped on Hiroshima on August 9th. Thereafter, she proceeded toward the Philippines and was sunk by a Japanese submarine, the I-58. But the ship was not missed due to the nature of its orders and the crew languished in the water with little water or food for four days before being seen, just by chance, by a scout plane. Nearly half died, suffering the horrors of dehydration, hypothermia, and then sharks attacks (there is no total of the shark attacks alone, because many of the men the sharks attacked were already dead; but it is considered the worst shark attack in history). Only 316 men survived of 1195.
The torpedoing of a ship going full speed in either of the world wars was next to impossible as evidenced by a comparison of the loss of the liner Lusitania in 1915, and Indianapolis thirty years later, and thereby shows how unlucky both ships were. Both submerged submarines had about one seventh or eighth the speed of the ships. Picture two persons standing on a football field, one at each end (one representing a submarine, and the other a ship). Assume that the range of the torpedoes was about ten steps. For every step the “sub” moves to get into position, the “ship” moves seven. Three steps by the sub and the ship has moved 21. There is simply no way a sub could chase down such a ship or even move into position for a shot. Lusitania was zig-zagging and just happened to zig directly in front of the U-boat. Indianapolis was not zig-zagging but headed almost directly at the Japanese sub.
While the American ship captain, McVay, was court-martialed, later cooler heads prevailed and he was reinstated. But his grief was such that it did not keep him from committing suicide in 1968.
Sources: War Beneath the Sea, by Peter Padfield, p. 465; Japanese Warships of World War II, A. J. Watts; Wikipedia.