1944: America Attacks Japanese Stronghold in Operation Hailstone
Feb 16
Operation Hailstone
America Attacks Japanese Stronghold
Truk in the Caroline Islands had been the main base for Combined Fleet since the pre-WW2 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. However, by early 1944 the American carrier forces in the Pacific had grown so monumentally in strength that attacks that would have been unthinkable a mere six months earlier became possible.
In early February 1944, Vice Admiral Marc Mitscher’s Task Force 58 was so powerful and had such a good recent history that he thought he could arrange an attack on Truk, which was code named Operation Hailstone. The presence of Japanese land-based aircraft on the island did not deter his wish to conduct this raid. Strategically, an attack on Truk by the Americans was also important, as the Japanese garrison might interfere with American operations in the Marshall Islands.

Mitscher arrived with an enormous force of five fleet carriers (Enterprise, Yorktown, Essex, Intrepid, and Bunker Hill), four light carriers (Belleau Wood, Cabot, Monterey, and Cowpens), seven battleships, and a full compliment of cruisers and destroyers. The fleet brought with it 500 aircraft.

To prevent this very kind of devastating attack, the Japanese had already withdrawn the majority of the heavy vessels to Palau a week earlier. A few light surface warships, merchant vessels, and transports were left behind. Vice Admiral Shigeru Fukudome noted post-war that these ships remained in Truk mainly because they had been so damaged that either they were not worth saving or could not get underway. In early Feb, United States Marine Corps B-24 reconnaissance aircraft appeared above Truk, and it confirmed the American intention to strike to the Japanese.

A small group of Japanese aircraft struck first between 1300 and 1500 on February 16. With the exception of a bomb hit on the starboard bow of battleship Iowa (which caused only light damage), the Japanese fighters were fought off with relative ease with anti-aircraft fire. A night time torpedo bomber attack damaged the carrier Intrepid, killing 11, and sending her to Pearl Harbor and San Francisco for repair for the next four months.
Between February 17 and 18, aerial strikes, surface engagements, and submarine attacks rained devastation upon anything Japanese on and near Truk. The most damaging aspect was the loss of 270 aircraft, for that they had been the force that checked back American shipping. The importance of this function for Truk was reaffirmed on February 20, two days after the Truk strike, when Admiral Mineichi Koga ordered naval aircraft from Palau and Rabaul to transfer to Truk.

Japanese naval losses were also significant. Some of the ships were destroyed in anchorage, while most others were intercepted by American vessels that enveloped the area. A total of 191,000 tons of shipping, which included three light cruisers (Agano, Katori, and Naka), six destroyers (Oite, Fumizuki, Maikaze, Hagio, Isogu, and Tachikaze), three smaller warships, two submarines, and 32 transports and merchant ships, were destroyed.
American losses were comparably minimal. A small number of men were killed in the Japanese attack before the main American strike, as previously stated. During the main strike, 21 American aircraft were lost to anti-aircraft fire, though many of the downed crew were rescued by naval vessels.

Truk was cut off from supplies and was reduced to near-uselessness. The garrison sat out the remainder of the war. Starvation nearly wiped out the garrison by the time Japan surrendered.
Source: Attack on Truk