USS Oglala (CM-4) During the Attack
On the morning of 7 December 1941 USS Oglala, flagship of the Pacific Fleet Mine Force, was tied up outboard of the light cruiser Helena. They were alongside Pier 1010 at the Pearl Harbor Navy Yard, with an eight-foot camel between them. Japanese torpedo planes of the first attack wave hit the cruiser with a single torpedo, which ran under Oglala to hit Helena's starboard side. The torpedo's explosion broke through the minelayer's port bilge amidships, and she rapidly took on water. A bomb that burst nearby caused further damage. With the marginal watertight integrity typical of older ships, Oglala's flooding could not be contained.
When it became clear that she might sink, Oglala was moved aft of Helena, so she would not pin the warship against the dock. About two hours after receiving her initial damage, she rolled over to port and sank beside 1010 dock. There Oglala became the object of a prolonged, and ultimately successful salvage effort.
Though Oglala was originally evaluated as a total loss, with the only salvage goal being to clear valuable pier space, it was ultimately decided to fully recover and repair the ship. The salvage effort was complex work, with the inherent difficulties of righting and refloating a capsized ship compounded by Oglala's poor stability. Fifteen to eighteen divers were kept busy for nearly 2000 underwater hours during the salvage, patching her hull, rigging chains, cutting away unwanted structure and executing many other tasks. After her tophamper had been removed, ten salvage pontoons were used to pull the ship upright while air was pumped into her to lighten the load. The first righting attempt, made on 11 April 1942, failed when several connecting chains parted. However, a second try succeeded twelve days later.
Oglala was now upright, but still mostly underwater. A large wooden cofferdam was built around the edges of her decks to allow water to be removed from her interior. The ship was refloated in June, but resank on 25-26 June when the failure of a pump led to cascading flooding in her forward hull. Afloat again on 29 June, she promptly went down for a third time when the cofferdam failed. After another raising, a serious fire on 2 July nearly produced a fourth resubmergence. However, the next day Oglala was finally drydocked, completing a job that became a legend among marine salvors. She received temporary repairs during much of the rest of 1942 and, in December, left Pearl Harbor for the U.S. west coast, there to be refurbished for active service.
