The battle of Kolombangara (13 July 1943) was fought in an unsuccessful attempt to prevent the Japanese getting more reinforcements from their main base at Rabaul to Vila, on the south-eastern shore of Kolombangara Island. From there the Japanese troops would be shipped across to Munda on New Georgia where they would help fight off an American invasion force that had landed earlier in July.
The American fleet was commanded by Rear Admiral Walden L. Ainsworth. His flagship was the light cruiser Honolulu and he also had the cruisers St. Louis and HMNZS Leander. The Leander had joined Ainsworth's force to replace the Helena¸ sunk a week earlier during the battle of Kula Gulf (6 July 1943).
Ainsworth had ten destroyers in two squadrons. Destroyer Squadron 21 (Nicholas, O'Bannon, Taylor, Jenkins and Radford) was his regular destroyer force and all but the Taylor had fought at Kula Gulf. He was also joined by Comdesron 12 (Captain Thomas J. Ryan) with the destroyers Ralph Talbot, Buchanan, Maury, Woodworth and Gwin. This new force joined Ainsworth late on 12 July and there was thus little time to coordinate their plans.
Ainsworth had a simple plan for the upcoming battle. Once the Japanese had been sighted the lead destroyers were to fire torpedoes. The cruisers would get into a firing position, overwhelm the Japanese with rapid gunfire and then turn away to escape any torpedo attack.
The Japanese fleet was commanded by Rear Admiral Izaki Shunji. His flagship was the light cruiser Juntsu. He also had five destroyers (Mikazuki, Yukukaze, Hamakaze, Kiyonami and Yogure) and four destroyer transports (Satsuki, Minazuki, Yunagi and Matsukaze). He also had the excellent 'long lance' torpedo, capable of hitting targets at a much greater range than any American torpedo. Admiral Ainsworth was unaware of the existence of this weapon.
The American fleet sailed west along the slot, the gulf between the northern and southern Solomon Islands. At first Ainsworth hugged the southern coast of Santa Isabel, one of the northern islands. At midnight on 12-13 July Ainsworth reached the western end of that island and turned south-west to head towards Visuvisu, at the north-western end of New Georgia and the north-eastern corner of Kula Gulf (between New Georgia and Kolombangara to the west).
Although none of the Japanese ships were equipped with radar, they did have a radar detection device. Using this they had picked up the first signs of the American fleet at around 11pm on 12 July and from midnight they were able to accurately plot their course.
The Japanese showed up on American radar at 1am, and were signed visually from the Nicholas, in the lead group, at 1.03. At 1.06 Ainsworth ordered his cruisers to turn thirty degrees to the right so that more of their main guns could fire on the Japanese, and at 1.09 he ordered the lead destroyers to fire their torpedoes. One minute earlier the Japanese had fired their own torpedoes.
The first part of the battle favoured the Allies. Their cruisers fired 2,630 6in rounds at the Jintsu and were soon scoring hits. Her steering gear went at 1.17 and her fire rooms were hit by at least ten shells. She was soon dead in the water, and was then hit by two torpedoes. The stricken cruiser broke in two and was devastated by a series of explosions. Admiral Izaki Shunji and 482 of his men were killed.
It was now the turn of the first Japanese torpedoes. At 1.17 Ainsworth ordered a turn to the south to keep the range between his ships and their targets at around 9,000 yards. This put them side on to the oncoming torpedoes, and at 1.22 the Leander was hit. The blow killed 28 men and forced her to drop out of the battle.
At 1.15 an American reconnaissance aircraft reported sighting four Japanese destroyers heading north. Ainsworth ordered Captain McInerney to take three of the five van destroyers and chase the Japanese, while the other two stood by the Leander. At 1.31 McInerney headed north-west (at 325 degrees).
In the meantime Ainsworth turned his cruisers to the north-east to get them out of the way of any further torpedoes. Ryan's rear destroyer squadron stayed with the cruisers. During this movement the cruisers continued to fire on the Jintsu. Between 1.38 and 1.42 Ainsworth turned back to a north-westerly course, heading towards what he believed were damaged Japanese destroyers. For a few crucial minutes all of the Japanese destroyers were unengaged.
The Japanese had taken advantage of this pause. The destroyer transports escaped along the coast of Kolombangara. They reached Sandfly Harbor on the west coast of the island and unloaded 1,200 troops, finishing at 3.40am. The escort destroyers reloaded their torpedo tubes in a remarkable 18 minutes and prepared for a second round.
The Japanese destroyers were picked up on American radar at 1.56am, but Ainsworth couldn't be certain that the new radar contact wasn't McInerney's destroyers. He attempted to contact each of his destroyers to check their locations. This took seven minutes and didn't entirely answer the question. At 2.03 he ordered his cruisers to fire star shells. By this point the Japanese had fired their second salvo of torpedoes and turned away to the north-west. This finally convinced Ainsworth that they were enemy ships and he ordered his cruisers to turn 60 degrees to the right and open fire with their main guns.
This put his ships directly into the path of the long lance torpedoes. At 2.08 the St Louis was hit in the bow. The Honolulu managed to avoid several torpedoes, but was hit in the tip of the bow. A second hit, in the stern, was a dud and fell off without causing any real damage. Neither cruiser suffered any serious casualties.
The destroyer Gwin suffered the worst damage. She was hit in the engine room amidships at 2.14. The hit caused an explosion and massive fires. The crew attempted to save the ship but were overwhelmed by the fires and had to be taken off. Two officers and 59 men were killed.
After this the Americans withdrew. Ainsworth called for air support, and at dawn fighter aircraft from the recently constructed bases on the Russell Islands fought off 18 Val dive bomber and 20 Zeros. Ainsworth's fleet limped back into Tulagi late on the afternoon of 13 July, where they received a hero's welcome.
Both sides overestimated the scale of their successes. The Japanese believed that they had sunk all three cruisers. All three ships remained afloat, but they all needed extensive repairs. Honolulu was given a new bow at Pearl Harbor before joining St. Louis in California for further repairs and a minor refit. They returned to the fleet in November 1943. The Leander was a lower priority, and spent 25 months being repaired and refitted at Boston. She didn't return to action. The Japanese had also landed all of their troops, so with some justification could claim to have won a costly victory.
The Americans knew they had sunk the cruiser Jintsu, but weren’t sure if they had sunk any destroyers. A reconnaissance aircraft reported seeing one destroyer sink, while a survivor from the Jintsu claimed that four destroyers had been lost. The Americans did learn one valuable tactical lesson from the battle - not to chase Japanese destroyers with their cruisers.