Truk atoll in the Caroline Islands had been the main base for the Japanese Combined Fleet since the pre-WW II days and had since been the home-away-from-home for the Combined Fleet vessels operating in the South and Central Pacific. For the first two years of the conflict, Truk was considered an unassailable bastion. To ensure air and naval superiority for the upcoming invasion of Eniwetok, Admiral Spruance ordered an attack on Truk in early Feb 1944, code named Operation Hailstone. US forces arrived with an enormous force of five fleet carriers (Enterprise, Yorktown, Essex, Intrepid, and Bunker Hill), four light carriers, seven battleships, and a full complement of cruisers and destroyers. The fleet brought with it 500 aircraft. Between 17 and 18 Feb, aerial strikes, surface engagements, and submarine attacks rained devastation upon anything Japanese on and near Truk. Japanese naval losses were significant. A total of 191,000 tons of shipping, which included three light cruisers six destroyers three smaller warships, two submarines, and 32 transports and merchant ships, were destroyed.
Wreck dives at Truk: