When the Japanese acquired the Caroline Islands from Germany as a League of Nations mandate after World War I, they found themselves in possession of Truk (present-day Chuuk), an atoll studded with islands that enclosed a natural deep-water harbor spanning 820 square miles. During World War II this “Gibraltar of the Pacific” was a key staging base for imperial ships and aircraft. Thus when the U.S. Navy invaded the Marshall Islands in late January 1944, Truk came under the sights of the Fast Carrier Task Force under Adm. Marc A. “Pete” Mitscher.
Launched that February 16, Operation Hailstone devastated the many Japanese bases on Truk, destroying or crippling more than 250 aircraft and sinking 32 transport ships, two light cruisers, four destroyers and four auxiliary vessels. The American attackers lost just 25 aircraft and 40 crewmen. By the time the American fleet departed on February 18, the bogey of the Japanese Gibraltar had been laid to rest. Follow-up carrier raids in late April finished its importance as a Central Pacific base. What remains is a seabed littered with the rusting and coral-encrusted remains of aircraft, ships and their cargoes, reminders for recreational scuba divers of the ferocious battle that once raged there.