The Battle of Empress Augusta Bay, on 1–2 November 1943 – also known as the Battle of Gazelle Bay, Operation Cherry Blossom, and in Japanese sources as the Sea Battle off Bougainville Island (ブーゲンビル島沖海戦) – was a naval battle fought in Empress Augusta Bay near Bougainville Island . The naval battle was a result of Allied landings at Cape Torokina with the bay in the first action in the Bougainville campaign of World War II and may also be considered as part of the Solomons and New Guinea campaigns. The battle was significant as part of a broader Allied strategy—known as Operation Cartwheel—aimed at isolating and surrounding the major Japanese base at Rabaul. The intention was to establish a beachhead on Bougainville, within which an airfield would be built.
The naval battle took place at the end of the first day of the landings around Cape Torokina, as the Japanese sortied a large force from Rabaul in an effort to replicate the success they had achieved at Savo Island in August 1942, in response to Allied amphibious landings in the eastern Solomon Islands. Ultimately, the covering force of US warships was able to turn back the Japanese force, and the landings around Cape Torokina were successful.
Background
On 1 November 1943, the 3rd Marine Division landed at Cape Torokina in Empress Augusta Bay on Bougainville Island. Following in the wake of Allied successes in the Solomon Islands campaign, the landings were undertaken as part of an Allied plan to establish airbases in the region to project airpower towards the Japanese stronghold around Rabaul, the reduction and isolation of which was a key part of Operation Cartwheel. The bay had been chosen because it was at the outer limit of Allied fighter plane range and because the numerically-superior Japanese 17th Army was concentrated at other, more strategic sites in the north and the south. The Marines were backed by Task Force 39, composed of cruisers and destroyers, commanded by Rear Admiral Aaron S. Merrill. Merrill's force was tasked with covering the vulnerable transports and minelayers from air attack and from attack from the sea.
The Japanese responded with air attacks and a powerful naval force from Rabaul commanded by Admiral Sentaro Omori, attempting to replicate the success they had achieved at Savo Island in August 1942, in response to Allied amphibious landings in the eastern Solomon Islands. The Japanese formation was hastily assembled from whatever ships were on hand, many of which had never trained or fought together before. Omori's force consisted of the heavy cruisers and , the light cruisers and , and the destroyers , , , , , and . These were organised into a cruiser division (Cruiser Division 5), which contained the two heavy cruisers, and two screens (left and right) with a light cruiser and three destroyers. The left screen was commanded by Rear Admiral Ijuin Matsuji, while the right was under Rear Admiral Morikazu Osugi's command. Initially, this force had included five destroyer transports laden with troops for a counter-landing, but following several delays, the decision was made for the transports to return to Rabaul. This force would later land around Koromokina Lagoon on 7/8 November.
Ranged against the Japanese force was Merrill's Task Force 39 (TF39). The heart of TF39 was Cruiser Division (CruDiv) 12 – , , , and . These four cruisers were officially categorized as light cruisers; however, they were nearly the size of the Japanese heavy cruisers and were armed with twelve radar-aimed rapid fire guns. TF39 also included Destroyer Squadron (DesRon) 23, which consisted of two destroyer divisions (DesDiv): DesDiv 45 – , , , and DesDiv 46 – , , , . Merrill had overall command of the force, as well as directly commanding CruDiv 12, while Captain Arleigh Burke commanded DesDiv 45 and Commander Bernard Austin was in command of DesDiv 46.