Meanwhile, U.S. Naval intelligence had strongly ascertained that the Japanese were planning an attack on the central Pacific island of Midway. Admiral Chester Nimitz, Commander-in-Chief, U.S. Pacific Fleet, determined to take the opportunity to engage them. Losing Midway would have been a very serious threat because the Japanese then could easily take Hawaii and threaten the west coast of the United States. The loss of his most aggressive and combat experienced carrier admiral, Halsey, on the eve of this crisis was a severe blow to Nimitz. Nimitz met with Halsey, who recommended his cruiser division commander, Rear Admiral Raymond Spruance, to take command for the upcoming Midway operation. Nimitz considered the move, but it would mean stepping over Rear Admiral Frank Fletcher of Task Force 17, who was the senior of the two men. After interviewing Fletcher and reviewing his reports from the Coral Sea engagement, Nimitz was convinced that Fletcher's performance was sound, and he was given the responsibility of command in the defense of Midway. Acting upon Halsey's recommendations, Nimitz then made Rear Admiral Spruance commander of Halsey's Task Force 16, comprising the carriers "Enterprise" and "Hornet". To aid Spruance, who had no experience as the commander of a carrier force, Halsey sent along his irascible chief of staff, Captain Miles Browning.