In addition to air attacks from Rabaul, which were thwarted by Allied fighter aircraft, the Japanese dispatched a scratch naval task force to attack the Torokina beachhead on Bougainville. Commanded by Rear Admiral Omori Sentaro, the force consisted of the heavy cruisers Myoko and Haguro, two light cruisers, six destroyers, and five destroyer transports carrying 1,000 troops who were to be landed on Bougainville. Rear Admiral Ijuin Matsuji commanded the left flank screen with the light cruiser Sendai and three destroyers, and Rear Admiral Osugi Morikazu had the right with the light cruiser Agano and three destroyers.
The transports turned back late in the evening of 1 November after Omori concluded that the task force had been sighted by American planes. Omori, however, continued to Bougainville with his other ships in the expectation that he could destroy the Allied transports and cargo vessels in a night battle. Unknown to him, the transports had been quickly unloaded and had left Empress Augusta Bay earlier that day.
Learning of Omori's task force from U.S. Army reconnaissance aircraft, Rear Admiral A. Stanton Merrill, whose Task Force 39 had been providing bombardment support for the Bougainville landing force, moved to intercept the Japanese about 20 miles north of Empress Augusta Bay. Task Force 39 was centered on Merrill's Cruiser Division 12, consisting of the light cruisers Montpelier (the flag), Cleveland, Columbia, and Denver. Captain Arleigh Burke's Destroyer Division 45 made up the van, and Commander B. L. Austin's Destroyer Division 46 comprised the rear. Merrill hoped to engage the Japanese ships at long range to avoid a torpedo attack while making use of his radar-controlled, 6-inch guns.
The two task forces encountered each other at 2:27 a.m. on 2 November and fought a complicated battle that was really three engagements in one: Merrill's cruisers against Omori's cruisers and individual battles waged respectively by the two destroyer divisions. Although the Japanese were superior in gunfire and torpedoes and although Omori thought he had inflicted serious losses on the Americans, he broke off the battle after an hour, at 3:27.
Merrill's cruisers sank the Japanese light cruiser Sendai, and Destroyer Division 46 sank the Japanese destroyer Hatsukaze, which already had been badly damaged in a collision with the cruiser Myoko, Omori's flagship. Task Force 39's losses were limited to damage to two ships; the destroyer Foote had her stern blown off by a torpedo. Merrill abandoned pursuit of the Japanese ships at dawn to await the inevitable Japanese air response from Rabaul. It came at about 8:00 a.m. in the form of 100 Japanese aircraft, which were met by a smaller number of Allied fighters. The Japanese inflicted only minor damage, with the cruiser Montpelier taking two bomb hits on her starboard catapult. Omori was subsequently relieved of command for failing to carry out his orders.
The Battle of Empress Augusta Bay did not end the Japanese naval threat to the Allied lodgment on Bougainville. However, the prompt U.S. Navy reaction prevented Japanese disruption of the landing, and along with massive air raids against Rabaul over the next days and the naval battle of Cape St. George on 25 November, it helped ensure the success of the Bougainville Campaign. John Kennedy Ohl
Gailey, Harry A. Bougainville: The Forgotten Campaign, 1943–1945. Lexington: University Press of Kentucky, 1991.; Morison, Samuel Eliot. History of United States Naval Operations in World War II. Vol. 5, The Struggle for Guadalcanal, August 1942–February 1943. Boston: Little, Brown, 1949.; Prados, John. Combined Fleet Decoded: The Secret History of American Intelligence and the Japanese Navy during World War II. New York: Random House, 1995.
John Kennedy Ohl