Battle off Horaniu

In mid-1943, in the wake of the Guadalcanal campaign, the Allies launched their next offensive in the Solomon Islands, focused upon seizing the major Japanese airstrip at Munda on New Georgia. After the fall of Munda on 4–5 August and defeat in the Battle of Vella Gulf on 6–7 August, the Japanese decided to evacuate their garrisons in the central Solomons, firstly moving to Baanga Island while planning to bring forces south from Rabaul for a potential counterattack. On 15 August, the Allies landed on Vella Lavella, bypassing the main Japanese troop concentration on Kolombangara. To maintain contact with these troops, and ensure their later withdrawal, the Japanese planned to establish a staging base at Horaniu, on the northern tip of Vella Lavella. Commanded by Captain Matsuji Ijuin, the destroyers , , , and left Rabaul on 17 August to rendezvous with a troop convoy from Buin, on Bougainville. This convoy included 13 barges, four motor torpedo boats, the subchasers and , and a . The troops embarked consisted of two Imperial Japanese Army companies and an Imperial Japanese Navy platoon. ==Battle==

(far left) After the Japanese force was located by Allied reconnaissance aircraft, Rear Admiral Theodore S. Wilkinson, commander of the Third Amphibious Force, dispatched a division of four destroyers from Purvis Bay on Florida Island to intercept them. This force consisted of , , , and , under Captain Thomas J. Ryan. They departed their anchorage at 15:27 on 17 August and began a fast run up the New Georgia Sound, also known as "The Slot". When Ryan's destroyers were off the north coast of Kolombangara, lookouts on watch saw a burst of anti-aircraft fire in the distance, giving away the position of the Japanese convoy. Despite a full moon, visibility was limited to due to low-lying clouds and intermittent rain showers. However, at about 23:30, the Japanese convoy was attacked by eight AirSols Avenger torpedo bombers and forced to scatter, although no ships were damaged. Two of the escorts, Isokaze and Shigure, sailing abreast, began herding the smaller craft back into formation, while Sazanami and Hamakaze continued on a northwesterly course. Ryan was advised by the Avengers the Japanese ships were still heading for Vella Lavella, although his destroyers were detected shortly afterwards by a Japanese reconnaissance aircraft, which began circling in preparation for an attack. The convoy was still reforming when at 00:29 on 18 August Ryan's radar detected the Japanese destroyers to the northwest at a range of , then the Japanese barges; at 00:32, Japanese lookouts spotted the U.S. destroyers, which had closed to . After a series of turns, the U.S. destroyers opened fire with radar-controlled 5-inch guns at 00:58, which damaged Hamakaze, while Chevalier loosed a salvo of four torpedoes towards Shigure from a distance of . This attack was unsuccessful. The Japanese ships laid down a smokescreen and began to zigzag to throw off the U.S. gunners' aim. Torpedo attacks by both Shigure and Isokaze were also unsuccessful and were followed by an inaccurate radar report that another U.S. naval force was advancing from the south. ==Aftermath==

As a result of the battle, a total of five Japanese auxiliary ships were sunk. This included two subchasers, two motor torpedo boats, and one powered barge with an unknown number of personnel killed or injured. Two destroyers, Hamakaze and Isokaze, were slightly damaged, although this was not significant and both took part in further actions three days later. == Notes ==