However, the majority of the troop carrying barges escaped by hiding along the Vella Lavella coast and subsequently completed their mission on 19 August.

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.

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.

[4] Commanded by Captain Matsuji Ijuin, the destroyers Sazanami, Hamakaze, Isokaze, and Shigure left Rabaul on 17 August to rendezvous with a troop convoy from Buin, on Bougainville.

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.

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.

[9][10] 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 9,000 yards (8,200 m).

At this time, Isokaze fired a torpedo salvo from 8 miles (13 km), which failed to score a hit but in return was damaged by an American 5-inch shell,[9][11] wounding several sailors.

Ryan turned back to locate the troop convoy, but the small craft had taken advantage of the destroyer contest to disperse; although the Americans managed to sink five, the majority subsequently escaped.

[9] Meanwhile, on Vella Lavella, Horaniu fell to Allied forces on 14 September, while the base's 600 personnel were pushed into a small perimeter on the northwestern part of the island.