When you think of shark attacks, you probably imagine surfers, divers, or other people who choose to be in the water with the giant predators when they’re mistaken for food – but the worst shark attack in history is actually the result of an event far more sinister.

And in this case, the sharks weren’t making mistakes – the humans beings treading water were, in fact, their intended prey.

The USS Indianapolis had delivered components of the atomic bomb that would later level Hiroshima before leaving Guam. It sailed alone toward the Leyte Gulf in the Philippines, where it was supposed to meet the USS Idaho and prepare for an invasion of Japan.

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The USS Indianapolis (CA-35) was a heavy cruiser of the United States Navy in World War two. The ship was named after the City Indianapolis and was a ship of the Portland-class. The commissioning was on the 15th of November 1932 and had a length of 186m, a width of 20m and a draft of 7m. With her 8×White-Forster boilers, she had a maximum speed of 32.7 knots (60.6 km/h; 37.6 mph) and had a displacement of 10,110 tons. USS Indianapolis had a armament of 3×3-203mm guns, of 8×127mm AA guns, of 16×28mm AA guns, of 24×40mm AA guns, of 14×20mm AA guns and of 2×3-pounder 47mm guns. ======================================= After her commissioning, the ship was under the command of Captain John M. Smeallie and had a lot of training maneuvers, for example off the Chilean coast or in the Guantánamo Bay. She also escorted President Franklin Delano Roosevelt on three different cruises, one trip to the Campobello Island, one trip to a naval review and one trip to South America. During the last cruise, President Roosevelt underwent his crossing the line ceremony on the 26 November 1936 with the words: "an intensive initiation lasting two days, but we have all survived and are now full-fledged Shellbacks". After the beginning of World War two, USS Indianapolis operated together with carrier task forces in the South Pacific and supported the New Guinea campaign with the attacking of Lae and Salamaua. Then the ship was transferred in Alaska area and supported the Aleutian Islands campaign with the attacking of Kiska Island and other operations, for example the conquest of Amchitka. In February 1943, she was on a patrol with two destroyers in the near of Attu Island and had sank the Japanese cargo ship Akagane Maru (3,150 t). Later in 1943, USS Indianapolis became the flagship of 5th Fleet and took part in many operations, for example the conquest of the Gilberts, Marshalls and Marianas Islands. The ship also took part in a lot of attacks on Japanese positions, for example the bombarding of the Kwajalein Atoll in January 1944 and participated in the Peleliu invasion in September 1944. ??????????????????

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A day later, shortly after midnight, a Japanese torpedo ripped the ship in half.

It sank in under 12 minutes, sending the 900 survivors (of 1196 crew) into the water.

There weren’t enough life rafts to hold everyone but there were life vests to go around, and as the men formed groups and began going through rations and trying to maintain some kind of order, they surely believed rescue would come – and soon.

They were wrong.

Instead, the sharks appeared, likely drawn by the blood and bodies in the water, ready to attack live victims. Their reported aggression leads most historians and experts to believe the sharks in question were oceanic whitetips – a particularly aggressive species that lives and feeds in open water.

The sailors did what they could, pushing the men who died away from the groups to draw sharks and moving away from anyone with an open or bleeding wound. The first person to open a can of SPAM paid the ultimate price, and the rest of the meat rations were tossed after that harrowing spectacle.

Days passed and the Navy did nothing, believing that reports of the ships sinking had been planted in an attempt to draw rescue ships into open water. The survivors dwindled, dying from thirst, heat, drinking seawater and suffering from salt poisoning. Those who were not in their right minds dragged healthy men into the water when they jumped, dooming even more to the depths.

After four-plus days in the water, a Navy pilot spotted the survivors and radioed for help, and when a second plane arrived, it dropped rafts and supplies before landing and attempting to gather the men most at risk – disobeying orders in the process.

Twelve hours later, the USS Doyle arrived and pulled 317 men from the water – nearly 600 had perished in the four days it took the Navy to respond. Not all of them were killed by sharks, with salt poisoning and exposure claiming lives, along with lack of access to clean water, but none of those men would have had to die had the Navy been quick to send rescue teams after the attack.

Lessons learned? Don’t expect that help will be there soon, and don’t mess with the oceanic whitetip shark.

And don’t eat SPAM, but you probably already figured that out on your own.

Also also, Nic Cage starred in a 2016 movie about the disaster called USS Indianapolis: Men of Courage.