When the wave of Japanese torpedo planes and bombers attacked the U.S. naval base at Pearl Harbor just before 8 am on December 7, 1941, their primary targets were the seven American battleships berthed along quays in the harbor, as well as the fleet’s flagship, USS Pennsylvania, which was in dry dock at the time of the attack. But of these eight battleships, all but two would rise again to fight the Axis, along with most of the smaller vessels sunk or damaged in the attack. Now, nearly 75 years after Pearl Harbor, take a closer look at how the U.S. Navy worked quickly and tirelessly to repair the fleet after the Japanese attack, an effort that the Naval History and Heritage Command has called one of history’s greatest salvage jobs.

Within the first 30 minutes of their surprise aerial assault on the U.S. naval base at Pearl Harbor, the Japanese had inflicted significant damage to the fleet of massive American battleships anchored there. By the end of the attack, USS Arizona was completely destroyed and USS Oklahoma had capsized, while the heavily damaged USS West Virginia, USS California and USS Nevada had sunk in shallow water.

The battleship USS Pennsylvania (center right), sits in drydock at Pearl Harbor, amid the ruins of the USS Cassin and USS Downes, after the Japanese attack, Honolulu, Oahu, Hawaii, December 7, 1941. (Credit: US Navy/Interim Archives/Getty Images)

In addition to the five battleships sunk outright, three other battleships, three cruisers, three destroyers and other smaller vessels were damaged in the attack, which also claimed 180 U.S. airplanes and inflicted some 3,400 casualties, including more than 2,300 killed. Yet nearly as soon as the devastating attack ended, efforts began to salvage the U.S. fleet and return the damaged ships to the water to fight against Japan and the other Axis powers.

Fortunately for the U.S. Navy, the fleet’s flagship, USS Pennsylvania, had been in dry dock on December 7, and sustained only superficial damage. USS Tennessee and USS Maryland had been moored inboard of the West Virginia and Oklahoma, respectively, and were also largely sheltered from the torpedo assault.

Once Pearl Harbor Navy Yard personnel, assisted by tenders and ships’ crewmen, began recovery work on the damaged ships, it proceeded swiftly. Within just three months, by February 1942, USS Pennsylvania, USS Maryland and USS Tennessee, along with the cruisers Honolulu, Helena and Raleigh; the destroyers Helm and Shaw; the seaplane tender Curtiss; the repair ship Vestal and the floating drydock YFD-2 were back in service or had been refloated and transported by steam to the mainland United States for final repairs. The most heavily damaged of the small ships, the Raleigh and Shaw, were returned to active duty by mid-1942.

American battleship USS Maryland, relatively unscathed in the surprise attack on Pearl Harbor. (Credit: Time Life Pictures/Getty Images)

As for the rest of the fleet, it was clear that the five other battleships, two destroyers, a target ship and a minelayer suffered more severe damage, and would require extensive work just to get them to the point where repairs could be made. A week after the raid, a salvage organization was formally established to work on these more heavily damaged vessels. Led by Captain Homer N. Wallin, previously a member of the Battle Force Staff, the Salvage Division scored one of its greatest triumphs when it refloated the USS Nevada in February 1942.

With one large and many small holes blown into its hull, USS Nevada had sunk in shallow water, which made salvage work possible but not easy. Navy and civilian divers made some 400 dives and spent around 1,500 hours working on the Nevada alone, and two men lost their lives after inhaling the toxic gases accumulated in the ship’s interior. After being refloated, repaired and steamed to Puget Sound Navy Yard in Washington State for more permanent repairs, the Nevada rejoined the active U.S. fleet in late 1942.

The salvage workers also refloated USS California in March 1942, USS West Virginia in June and minelayer Oglala by July. After extensive repairs, these vessels also rejoined the fleet. The three other heavily damaged ships— Oklahoma, Arizona and the capsized target ship Utah—would not return to service. USS Arizona, which was destroyed after the explosion of an armor-piercing bomb caused a fire in its forward main magazines, remains on the floor of the harbor even today, serving as a memorial to those lost on December 7, 1941. The hull of USS Utah also remains in the harbor. A massive effort raised the Oklahoma, but the ship was ultimately too damaged to return to service.

Black smoke pouring from USS California on fire in Pearl Harbor after the surprise attack by the Japanese.
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A naval survey concluded that USS Oklahoma and USS Nevada appeared to have been lost because of design defects, while USS West Virginia had lacked the proper defenses to withstand such an attack. In the case of USS California, later investigation revealed that a number of manhole covers were left off or loose at the time of the attack, and there were not enough pumps onboard the ship to prevent the flooding from spreading and sinking the vessel.

According to the Naval History and Heritage Command account, Navy and civilian divers spent a total of some 20,000 hours underwater during the salvage operations, making around 5,000 dives. Most of the time, the divers had to wear gas masks to avoid toxic fumes from the oil-fouled ships. In addition to ship cleaning, salvage and repair, their work included recovering human remains, documents and ammunition.

Initially, the Japanese believed they had scored a key victory on December 7, 1941. But thanks to the heroic salvage effort, the great majority of the U.S. battleships and other vessels attacked at Pearl Harbor would survive to take on the Axis in World War II. On D-Day in June 1944, USS Nevada inflicted heavy shelling damage on German emplacements behind the beaches of Normandy, France. Later in 1944, during the U.S. invasion of Philippines, USS West Virginia, USS California, USS Tennessee, USS Maryland and USS Pennsylvania—all supposedly “lost” at Pearl Harbor—joined USS Mississippi in bombarding approaching Japanese naval forces in the Surigao Strait.