Operation Hailstone, the strikes on Truk, had been planned for April 1944, but the Americans had progressed through the Pacific faster than expected. On February 4th 1944, American photo intelegance from Truk Atoll showed the harbour being used as a forward anchorage for the Japanese navy and the US hoped for a significant presence of capital ships. The Japanese battleship Musashi was photographed at Truk in early February.

Operation Hailstone

Taskforce 58 consisted of nine aircraft carriers, and seven battleships, with over 500 aircraft at their disposal - roughly than twice the number of Japanese aircraft stationed on Truk. Having taken the Marshal Islands quicker than expected, the US turned their attention to Truk with Operation Hailstone being launched on February 17th and 18th 1944.

Before dawn on February 17, the fleet carriers of Task Force 58 launched F6F Hellcats in order to clear the skies of hostile aircraft. Arriving over Truk at first light, they found little initial resistance from the Japanese forces the Japanese Combined Fleet had dissapeared from the harbour.

The first waves of bombers carried armour piercing bombs with the purpose of hitting the major warships in the harbour. However, it soon became apparent that Truk had been abandened by the Japanese Navy and no major warships remained. The remaining bombing waves were therefore loaded with more general purpose amunition aimed at merchant shipping and shore based targets.

A night attack from USS Enterprise was to use Radar guidance for the first time in a naval attack.

On February 18th, three more bombing runs were mounted against Truk, but it was becoming obvious that the base had been levelled, and the advantage to be gained from further attacks was not worth the risk. Taskforce 58 was therefore withdrawn to its anchorage at Majuro Atoll in the Marshal Islands.

After the battle, the US had lost 25 aircraft, and the Carrier USS Intrepid had been slightly damaged, however the Japanese had lost over 260 aircraft and 45 ships totalling 220,000 tons.

"The Pacific Fleet has returned at Truk, the visit made by the Japanese Fleet at Pearl Harbour..."  Fleet Admiral Chester Nimitz.

The Expedition

The expedition was organised by Ron Benson at Going Under Diving in Minnesota and exclisively targetted rebreather divers in order to undertake extended dives on Truk Lagoons World War 2 wrecks. The team consisted of 7 Megladon rebreathers, 6 KISS rebreathers, and 2 Inspiration rebreathers.

We stayed at Blue Lagoon Resort and dived with off their boats. Generally we had a maximum of 4 divers per boat in order to ensure enough space for all our equipment.

The team used trimix 10/50 for Diluent, and offboard bailout consisting of a trimix bottom bailout, and oxygen for deco.