Battle of Midway
To battle with an enemy expected to have four or five carriers, Admiral Chester W. Nimitz, Commander in Chief, Pacific Ocean Areas, needed every U.S. carrier he could get. He already had Vice Admiral William Halsey's two-carrier (Enterprise and Hornet) force. Halsey was sick with psoriasis and had to be replaced by Rear Admiral Raymond A. Spruance. Nimitz also called back Rear Admiral Frank Jack Fletcher's force, including the carrier Yorktown (which had major damage at Coral Sea), from the South West Pacific Area. It reached Pearl Harbor just in time to sail.