Operation hailstone was a large scale naval air and surface attack performed by the US Navy against the Japanese naval and air base at Truk. Allied victory over the Japanese on Truk helped insure allied air and naval superiority during the invasion of Eniwetok(which would allow the American navy to have a forward base for later operations during the war).

In addition to being a logistical base, Truk was the home base for the Japanese Royal navy since before the beginning of WWII. Also, it was a major support for various other Japanese garrisons on other islands in the south pacific.

At the beginning of WWII, Truk was considered invincible and impervious to allied assault, but thanks to the growth in US naval carrier forces, by February of 1944, that was no longer the case. A week prior to the operation, the Japanese navy had removed many of their ships to Palau bay, but many battleships and merchant vessels still remained.

The allied forces, led by Vice Admiral Marc Mitscher, consisted of 54 ships(including 9 carriers), 10 submarines, and 598 planes. Fighting began when Japanese aircraft attacked in the afternoon on the 16th of February. Save for a single bomb hitting the Iowa, no major damage was incurred until the actual operation which began the next day.

The operation consisted primarily of air strikes, surface ship actions, and submarine attacks over the course of two days. The American forces managed to inflict major damage to the Japanese forces present, including the destruction of 270 aircraft that had been used by the Japanese to disrupt American shipping.

Because of the staggering amount of damage the American forces had done to the Japanese forces at Truk, Admiral Mineichi Koga ordered naval aircraft from both Palau and Rabaul to transfer to Truk, which were later attacked by American carriers two months later.

The American forces managed to complete the operation with very few losses, which consisted of 11 men, and just over 20 aircraft. The Carrier Intrepid suffered enough damage to cause it to be sent back to Pearl Harbor and San Francisco for repairs that would take four months to complete.

American victory at Truk resulted in Truk’s isolation for the remainder of the war. Cut off as it was from Japan, the remaining Japanese forces ran low on food and were facing starvation before the Japanese would finally surrender in August of 1945. This resulted in further victories in the Marshall islands as the Allied forces moved ever closer to Japan.