Marshall and Gilbert raids expose the Japanese perimeter

Fletcher's Yorktown force and Halsey's Enterprise force attacked separated island groups on 1 February 1942. Their aircraft and accompanying surface bombardments damaged ships, aircraft, garrisons, and installations, though the Americans also lost several carrier and cruiser floatplanes. Japanese carriers were diverted to search for task forces that had already withdrawn, imposing a cost even after the shooting ended. The raids gave American crews combat experience and a morale boost while revealing that the widely spaced Japanese garrisons could not support one another against a mobile carrier force. The weakness first attracted notice at lower levels, and how quickly senior commanders accepted it remains disputed. That vulnerability helped reinforce Isoroku Yamamoto's desire to force the American carriers into an early decisive battle.