The Story of USS Indianapolis, a Top-Secret Mission, and the Worst Sea Disaster in US Naval History
She fought in the bloodiest battles of World War II—and delivered the secret that ended it.
USS Indianapolis had seen the fires of war, from bombardments in the Gilberts to strikes deep into the Pacific. But in July 1945, she was given a mission unlike any other: delivering components of the first atomic bomb to Tinian.
No escort. No recognition. Just speed, secrecy, and trust.
Indianapolis and her crew succeeded in their secret mission and set course for the Philippines. But just after midnight on July 30th, a Japanese submarine spotted the cruiser and torpedoed her twice.
In less than twelve minutes, Indianapolis slipped beneath the waves, leaving nearly 900 men stranded in open ocean. And for four days, no help came.
When a passing patrol plane finally spotted the survivors, it was too late for most of them. Shark-infested waters, searing heat, and a lack of food and water had exacted a terrible toll. Of the 900 who went into the sea, only 316 were rescued, making it the deadliest single ship disaster in US Navy history.
This is the story of the USS Indianapolis, the cruiser betrayed by silence.
Plot Points
Built for Battle
USS Indianapolis’ story began as steel and ambition before becoming a battle-hardened warrior.
One of only two Portland-class cruisers, she was built under the limitations of the Washington and London Naval Treaties, which aimed to prevent a naval arms race after World War I. Despite the constraints, these warships were designed to be fast, powerful, and adaptable.
Originally classified as a light cruiser due to her thin armor, Indianapolis was reclassified as a heavy cruiser in 1931. She was laid down at the New York Shipbuilding Corporation on March 31, 1930, launched on November 7, 1931, and commissioned into the fleet on November 15, 1932.
Her armament included nine 8-inch guns housed in triple turrets, eight 5-inch anti-aircraft guns, and an array of smaller cannons that expanded as the war progressed. Though her armor was modest, just five inches protecting her magazines and 2.5 inches shielding her deck and gunhouses, but it was strategically placed to defend her most vital areas.
Originally built to carry over 800 officers and sailors, her wartime role as a fleet flagship swelled her complement to over 1,200.
Into the Fire
When the attack on Pearl Harbor thrust the United States into World War II, USS Indianapolis was already at sea. On December 7, 1941, the cruiser led Task Force 3 in a mock bombardment near Johnston Atoll.
In the days that followed, Indianapolis joined the hunt for the Japanese carriers responsible for the surprise attack. Scouring the Pacific without success, she returned to a reeling Pearl Harbor on December 13.
First Clashes
Indianapolis was soon steaming south as an escort to the aircraft carrier USS Lexington. On February 20, 1942, Japanese aircraft ambushed the group, but American fighters combined with shipboard gunners helped repel the attack.
On March 10, now joined by USS Yorktown, the American warships launched a surprise attack on Japanese forces in New Guinea, sinking and damaging several enemy ships. After the operation, Indianapolis returned to Mare Island in California for a refit.
War in the Aleutians
With the war spreading across the Pacific, Indianapolis shifted north to support the Aleutian Islands campaign. In August 1942, she shelled Japanese defenses on Kiska Island through heavy fog, clearing the way for US forces to seize Adak.
Early in 1943, she helped support the landings at Amchitka and sank the Japanese freighter Akagane Maru after a failed radio challenge. Through mid-1943, Indianapolis patrolled the Aleutians, escorted convoys, and continued to bombard enemy positions. American troops eventually captured Attu, forcing a Japanese evacuation of Kiska.
Striking South
After another overhaul, Indianapolis returned to the Central Pacific as the flagship of Vice Admiral Raymond A. Spruance. Departing Pearl Harbor in November 1943, she led the Southern Attack Force during Operation Galvanic, the invasion of the Gilbert Islands, bombarding Tarawa and Makin Atoll.
Victory in the Gilberts paved the way for assaults on the Marshall Islands. In January 1944, Indianapolis battered Japanese defenses at Kwajalein with a devastating creeping barrage, and remained in the lagoon until resistance collapsed.
Blows Against the Empire
As flagship, Indianapolis supported carrier strikes on the Caroline Islands, helping to cripple Japanese shipping at Palau. In June, she spearheaded bombardments at Saipan during the Marianas invasion, then raced to intercept a Japanese fleet in the Battle of the Philippine Sea, known as the ‘Great Marianas Turkey Shoot,’ where the United States destroyed over 400 Japanese planes and sank three enemy carriers.
Returning to Saipan, she provided support shelling Tinian and became the first ship to reenter Apra Harbor in Guam. Later, she shelled Japanese defenses at Peleliu for over two weeks before returning to California for an overhaul.
Toward Japan
In November 1944, Captain Charles B. McVay III took command of Indianapolis. Fresh from refit, she joined Vice Admiral Marc Mitscher’s fast carrier task force in early 1945.
On February 16, Indianapolis took part in the first carrier strikes on Tokyo since the Doolittle Raid. Exploiting bad weather, US forces destroyed nearly 500 Japanese aircraft and hammered military targets.
Soon after, she steamed to the Bonin Islands to support the invasion of Iwo Jima, pounding enemy positions and protecting invasion ships. She then returned for a second wave of strikes on Tokyo, destroying more planes and even more enemy shipping.
Into the Chaos
With Iwo Jima secured, the final approach to Japan began with the invasion of Okinawa. Departing Ulithi on March 14, Indianapolis launched strikes on Kyūshū and bombarded defenses on Okinawa itself.
Kamikaze attacks became relentless. On March 31, a Japanese fighter broke through the defenses and dropped a bomb from just 25 feet above Indianapolis’ deck before crashing into the sea.
The bomb tore through her deck, into the crew’s mess hall, through the berthing compartment, and the fuel tanks, before crashing through the keel and exploding beneath the ship. The blast blew gaping holes in Indianapolis, flooding nearby compartments and killing nine crewmen.
Damaged but still afloat, she made her way under her own power to Mare Island for repairs. She had survived the fiercest campaign of the Pacific, but her most fateful mission was still to come.
Transporting the Atomic Bomb
Following major repairs, USS Indianapolis received orders for a top-secret mission: delivering components for the world’s first atomic bomb.
In her hold was the complete non-nuclear assembly of Little Boy, the gun-type atomic bomb, along with hundreds of pounds of instruments and specialized tools. Safely secured inside a lead-lined steel container in Captain McVay’s quarters was the bomb’s most critical element: 85 pounds of enriched uranium.
Two representatives from the Manhattan Project, Major Robert Furman and Dr. James Nolan, accompanied the shipment incognito. Nolan, the Chief Medical Officer of Los Alamos, was tasked with monitoring radiation levels. Frequently seasick, he used his condition as a cover to inspect the uranium during the voyage.
Indianapolis departed San Francisco on July 16, 1945, just hours after the successful Trinity test in New Mexico. She made record time to Pearl Harbor, completing the trip in just over 74 hours, before continuing unescorted across the Pacific. The ship arrived at Tinian Island on July 26.
Before the bomb was loaded onto the Enola Gay, members of the ground crew wrote their names and messages onto the weapon. One read: “Greetings to the Emperor from the men of the Indianapolis.” The bomb would be dropped on Hiroshima on the morning of August 6.
With her secret mission complete, Indianapolis steamed to Guam, where sailors who had completed their tours were rotated out. She then set course for Leyte, where the crew would prepare for the invasion of Japan.
But Indianapolis would never reach her destination.
The Sinking of USS Indianapolis
Around midnight on July 30, 1945, USS Indianapolis was steaming through the Philippine Sea when she was spotted by Japanese submarine I-58, commanded by Captain Mochitsura Hashimoto.
Hashimoto, mistakenly believing the cruiser was the battleship Idaho, fired a spread of six torpedoes. At 12:15 a.m., Indianapolis was struck by two—the first hit near her bow, the second amidships, causing catastrophic damage. The ship quickly took a sharp list to starboard and began to settle by the bow.
Just twelve minutes later, Indianapolis capsized. Her stern briefly rose from the water before she slipped beneath the waves. About 300 of her 1,195 crewmen went down with the ship. The remaining 890 sailors were left stranded in open water, many without life jackets or rafts.
A Delayed Rescue
No immediate alarm was raised despite the cruiser’s failure to arrive in Leyte on July 31. Indianapolis was incorrectly marked as having arrived. Those responsible for tracking her movements noted the mistake but failed to investigate.
At first, the Navy claimed no distress signals were received. However, declassified records later revealed that three different stations had picked up emergency transmissions from Indianapolis. One of the receiving officers was drunk, another ordered himself not to be disturbed, and a third dismissed the report as a Japanese ruse.
The Navy remained unaware of the disaster for over three days.
Discovered by Chance
On the morning of August 2, 1945, Lieutenant Wilbur “Chuck” Gwinn and his copilot, Lieutenant Warren Colwell, spotted survivors while flying a PV-1 Ventura patrol bomber. They were soon joined by a PBY-2 Catalina piloted by Bill Kitchen.
Gwinn dropped a life raft and a radio transmitter, triggering a massive rescue effort. Every nearby ship and aircraft capable of responding was dispatched.
Lieutenant Commander Robert Adrian Marks, flying an amphibious PBY-5A Catalina, was the first to arrive. After dropping more life rafts, with one being destroyed on impact, Marks saw that many of Indianapolis’s survivors were too weak to swim.
With orders not to land, Marks put it to a crew vote. With their support, he defied orders and landed in 12-foot swells. He and his crew pulled 56 sailors from the water, tying some to the wings with parachute cords when the plane grew overcrowded.
The Catalina, too damaged to take off, remained afloat until the destroyer escort Cecil J. Doyle arrived that night. She and six other ships ultimately rescued the survivors. Doyle later sank the Catalina to prevent it from falling into enemy hands.
Ordeal in the Water
The survivors of the Indianapolis endured unimaginable suffering. Many were wounded; all battled dehydration, sunburn by day, and freezing temperatures by night. While a few found scraps of food among the debris, most had nothing but their life jackets—if even that.
Shark attacks were relentless. Survivors described seeing hundreds of fins slicing through the water around them. Out of the nearly 900 men who entered the sea, only 316 were rescued. Two later succumbed to their injuries in August 1945.
The loss of Indianapolis remains one of the greatest disasters in US Navy history.
The Court-Martial of Captain McVay
Captain Charles McVay survived the sinking but was court-martialed in November 1945. He faced two charges: failing to order abandon ship and “hazarding” Indianapolis by not zigzagging.
McVay was acquitted of the first charge but convicted on the second. The trial was highly controversial. His orders had allowed him discretion on zigzagging depending on conditions. Even Captain Hashimoto, who commanded the submarine that sank Indianapolis, testified that zigzagging would not have saved the ship.
Despite his conviction, Fleet Admiral Chester Nimitz overturned McVay’s sentence and restored him to active duty. McVay retired as a rear admiral in 1949.
Still, the burden of blame weighed heavily on him. Some grieving families held him responsible for their loss and sent him hate mail for decades. One letter he received read, “Merry Christmas! Our family’s holiday would be a lot merrier if you hadn’t killed my son.”
The constant burden of guilt wore McVay down, and in 1968, he was found dead in his garden, with a service revolver by his side.
The Long Fight for Justice
Decades later, a sixth-grade student named Hunter Scott researched the Indianapolis tragedy for a school project. His work helped reignite national attention to McVay’s story.
On September 14, 1999, survivors, historians, and Navy officials testified before the Senate Armed Services Committee. Their voices made an impact, and in October 2000, Congress passed a “Sense of Congress” resolution officially exonerating Captain McVay. President Bill Clinton signed the resolution soon after.
The resolution also noted that McVay was the only US captain court-martialed during World War II for losing a ship to enemy action.
Reliable Thoughts
The story of USS Indianapolis is one of unimaginable heroism, horror, and heartbreak. Hundreds of sailors fought not just Japanese warships and planes, but an even greater enemy—nature itself: the sea, the sun, and the sharks. Clinging desperately to life in an endless ocean, they endured against impossible odds.
In the aftermath, Captain McVay bore the blame for a tragedy he could not have prevented. It was a burden that haunted him to the end.
Yet history did not forget. Through the determination of survivors, the efforts of a student, and the perseverance of those seeking the truth, justice finally rose from the depths. The Indianapolis and her crew are for how bravely they endured.
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