The US Navy launched a massive attack against the "japanese Pearl Harbor". Truk Lagoon was the major supply harbor in the south pacific, welcoming up to 1 000 vessels at a time. In feb, 1944, it has not only merchant ships, but also a significant part of the Japanese war fleet : super battleships, aircraft carriers, heavy cruisers, and on land, hundreds of zero fighters, and ten of thousands of soldiers.
48h before the raid, a US PBY was spotted over the lagoon, and the japanese admiral decided to withdraw immediatly his fleet to Palau, leaving the cargo ships unprotected.
After the raid, the airfields were severely damaged, hundreds of aircrafts destroyed in air combat or on the ground and most ships sunk.