Battle off Horaniu

On 15 August 1943 American forces land on the island of Vella Lavella. The Japanese had decided that due to heavy losses, all troops south of Bougainville would be evacuated. To perform this task the Japanese would need to establish a forward staging base and barge depot. The site for this was decided for Horaniu on the NE portion of Vella Lavella Island. A group of 20 barges and other auxiliary ships escorted by four destroyers, consisting of Sazanami, Hamakaze, Isokaze, and Shigure, left Buin on 17 August under the command of RADM Baron Matsuji Ijuin.

Allied air patrols sighted the Japanese and informed RADM Wilkinson of the Japanese movements. Captain Thomas Ryan was sent with the destroyers Nicholas, O’Bannon, Taylor, and Chevalier to intercept. Moving up the slot at high speeds, Ryan’s force of destroyers was spotted by Japanese scout planes and relayed the info to Sazanami, who was carrying the admirals flag.

The Japanese soon found themselves under attack when 8 TBF Avengers attacked the Japanese destroyers at around 2330. No damage was done but Ijuin decided to turn back and reorganize his ships after they became dispersed while fighting off the Allied air attack. He was also hoping to prevent a similar attack to the Battle of Vella Gulf, where the American destroyers used the island of Kolombangara to mask there approach.

At 0029 American radar picked up the Japanese, while almost simultaneously the Japanese lookouts sighted the American destroyers. Both destroyer groups where on a western course running roughly parallel at 20000 yards distance with the Japanese convoy moving ESE and closer to the Americans than its own escort. Ijuin assumed that the American ships would move in and slaughter the convoy with torpedoes, and moved to reform his line. Ryan however had different plans.

Thinking he had achieved surprise, Ryan had decided to catch the Japanese destroyers and attack in a nighttime torpedo action. At 0040 it became apparent that there was to be no surprise this night when Japanese floatplanes dropped flares and illuminated Ryan’s force. The Japanese fired a total of 31 torpedoes at the Americans between 0046-0055. All missed as Ryan unexpectedly turned north to chase the Japanese destroyers rather than attack the convoy.

Hamakaze and Sazanami turned south and opened fire while Isokaze and Shigure waited 2 minutes before making the same move. Chevalier fired four torpedoes at 0058 while the lead Japanese destroyer group turned back to the northwest. Shigure also fired a spread at this time but to no effect. With the range opening the rear destroyer group traded salvos with the Americans until at around 0115. At this time, the radarman on Hamakaze detected a large American force. With this false information Ijuin believed to be outgunned and outnumbered, and decide to retire from the battle.

Ryan would give chase for 5-10 minutes before turning back to attack the convoy. During the action the convoy had spread out and found some refuge along the northern coast of Vella Lavella. The American destroyer group would sink only two sub chasers and two barges. Ryan had blown his opportunity as the convoy was able to get away.

Both sides where particularly displeased with the way the battle had been fought. Two Japanese destroyers had been damaged, but not enough to keep them from operations. The next day the Japanese set up the staging base for the evacuation of troops. Kolombangara’s isolated troops where soon to be rescued.