The destroyer Cassin, No. 372 of the Mahan Class, shared the same specification as her sister ships Case and Shaw. On 7 December she was in Drydock No.1 in the Navy Yard alongside another of her sisters, Downes, and forward of the battleship Pennsylvania. She was not prepared for action. Her machine gun ammunition was not belted and the breech blocks of her 5-inch guns had been removed for modification. Nor could her crew see very much for they were at the bottom of the drydock. The ships in this dock went unscathed in the First Attack Wave but were not so fortunate in the Second Attack Wave. Lieutenant Commander Daniel Shea, captain of the Cassin anticipated this by ordering the closing of ports so that when the dock was flooded his ship could float. At 0905 Val dive-bombers attacked. A bomb fell between the two destroyers then two hit Downes and one Cassin on the stern before two more fell on the superstructure. Without power, the ship's fire hose pumps could not operate. Machines of the base fire department rushed to the scene to do what they could. At 0920 water began to enter the drydock, lifting burning oil and igniting ammunition on the destroyers. Cassin rolled over against her sister ship, still burning and with water being played on her depth charges to keep them cool enough not to explode. It was not until 1045 that the conflagration ceased, but the hull was, by then, a complete loss. She was righted on 5 February 1942 and removed from the drydock two weeks later. She was "repaired" by building a new hull to take her salvaged machinery and returned to service in February 1944.