Returning to Japan in 1931, Mikawa taught briefly at the Naval Academy before he took command from 1931 to 1936 of the cruiser Aoba, then the cruiser Choka, and finally the battleship Kirishima. Promoted to rear admiral in 1936, Mikawa was appointed chief of staff of the Second Fleet. In 1937, he became chief of the Intelligence Department of the Naval General Staff, and in 1940, he took command of the 5th Cruiser Squadron. Promoted to vice admiral in November 1940, Mikawa assumed command of the Battleship Division 3 in September 1941 and had charge of the Support Force of the Battleship 3 and Cruiser Division 8 for the Japanese attack against Pearl Harbor on 7 December 1941.
In July 1942, Mikawa received command of the newly formed Eighth Fleet and Outer South Seas Force at Rabaul. He thus was in charge of Japanese naval forces during the prolonged naval struggle off Guadalcanal, and in the course of this campaign, he administered the worst defeat ever suffered by the U.S. Navy in a stand-up fight—the 9 August 1942 Battle of Savo Island. Mikawa sank four Allied heavy cruisers and one destroyer, with no ships of his own lost in the battle (an American submarine torpedoed and sank the heavy cruiser Kako on the return to Rabaul), but he also withdrew without attacking the vulnerable Allied transports in the sound, for which he was later criticized by naval historians.
Mikawa commanded the covering force for Japanese carriers in the Battle of the Eastern Solomons on 22 to 25 August 1942. In June 1944, he took command of the Southwest Area Fleet and the Thirteenth Air Fleet at Manila. Concurrently commander of the Southern Expeditionary Fleet (from August to November 1944), he was attached to the Naval General Staff before he was transferred to the reserves in May 1945. Mikawa died at Kamagawa Prefecture, Japan, on 25 February 1981. Hirama Yoichi
Dull, Paul S. A Battle History of the Imperial Japanese Navy, 1941–1945. Annapolis, MD: Naval Institute Press, 1978.; Hammel, Eric. Guadalcanal: Decision at Sea—The Naval Battle of Guadalcanal, November 13–15, 1942. Novato, CA: Pacifica Press, 1988.; Loxton, Bruce, with Chris Coulthard-Clark. The Shame of Savo: Anatomy of a Naval Disaster. Annapolis, MD: Naval Institute Press, 1997.; Truscott, Lucian K., Jr. The Twilight of the U.S. Cavalry: Life in the Old Army, 1917–1942. Edited and with Preface by Lucian K. Truscott III and Foreword by Edward M. Coffman. Lawrence: University Press of Kansas, 1989.