The USS Indianapolis was one of the most famous U.S. warships lost in World War 2, and its sinking and subsequent loss of life was due to its secret mission and provoked great controversy.
The Indianapolis had been involved in several battles during WWII, and at one point had survived a direct bomb-strike due to the bomb completely passing thru the ship before exploding in the water underneath its hull.
It was on a top-secret mission immediately before it was sunk by the I-58 on its return voyage.
The mission? Delivering parts, including the uranium core of the atomic bomb that was dropped on Japan on August 6.
Although about 900 of the 1,200 crew survived the attack and sinking of the Indianapolis, only slightly more than 300 were still alive when rescue ships finally arrived four days later. The other 600 initial survivors had succumbed to thirst, exhaustion and shark attacks.
The sinking of the USS Indianapolis still represents the deadliest single loss of life at sea in the history of the US Navy.