Launched in , it was the flagship of the commander of Scouting Force 1 for eight years, then flagship for Admiral Raymond Spruance from to while he commanded the Fifth Fleet in battles across the Central Pacific during World War II.
In July , Indianapolis completed a top-secret high-speed trip to deliver uranium and other components for " Little Boy ", the first nuclear weapon used in combat, to the Tinian Naval Base , and subsequently departed for the Philippines on training duty. At on 30 July, the ship was torpedoed by the Imperial Japanese Navy submarine I , and sank in 12 minutes. Of 1, crewmen aboard, about went down with the ship.
The remaining faced exposure , dehydration , saltwater poisoning , and shark attacks while stranded in the open ocean, with few lifeboats and almost no food or water. The Navy learned of the sinking four days later, when survivors were spotted by the crew of a PV-1 Ventura on routine patrol. Navy PBY flying boat crew landed to save those in the water. Only survived.
On 19 August , a search team financed by Microsoft co-founder Paul Allen located the wreckage in the Philippine Sea lying at a depth of approximately 18, ft 5, m.
Indianapolis was the second of two ships in the Portland class, the third class of "treaty cruisers" constructed by the United States Navy following the Washington Naval Treaty of , after the two vessels of the Pensacola class , ordered in , and the six of the Northampton class , ordered in Navy in fiscal year , Indianapolis was originally designated as a light cruiser because of her thin armor and given the hull classification symbol CL She was reclassified a heavy cruiser , because of her 8-inch mm guns, with the symbol CA on 1 July , in accordance with the London Naval Treaty.
