The Americans invaded Vella Lavella Island on August 15, 1943, bypassing Kolombangara's garrison of 10,000 Japanese troops.  The Japanese, discouraged by heavy losses suffered fighting in the southern Solomons, decided to pull in their horns and evacuate all forces south of Bougainville. To facilitate this difficult task they moved to establish a barge depot and staging base at Horaniu on the northeast tip of Vella Lavella.  A flotilla of thirteen Diahatsu barges and three motor torpedo
boats carrying two companies of army troops and a naval platoon, screened by two subchasers, two armed Daihatsus, a motor torpedo boat, and an armored boat left Buin on 17 August bound for Horaniu.  Destroyers Sazanami, Hamakaze, Isokaze and Shigure commanded by Rear-Admiral Baron Matsuji Ijuin flying his flag on Sazanami provided the heavy escort.

Aerial reconnaissance alerted Rear-Admiral Wilkinson, commander of the Third Amphibious Force, to this movement.  To intercept he dispatched his screen commander Captain Thomas Ryan with four destroyers that had just completed refueling at Purvis Bay: Nicholas, O'Bannon, Taylor and Chevalier.   Their approach up the Slot at 32 knots did not go unnoticed by Japanese air scouts.  Hara writes:  "I was relieved to know something about the enemy's movements.  It was so much better than my last mission when we had to advance with no knowledge of the enemy deployment."

The moon was full, but with clouds below 2,000 feet and periodic squalls, visibility was limited to about three miles.  At about 1130 eight Airsols Avengers attacked the Japanese destroyers.   The Japanese formation became dispersed while repelling this attack.  Then, as they approached the dark mass of Kolombangara's eastern shore, Ijuin ordered a 180° change in course back toward the west, anxious to avoid conditions similar to those present during the devastating ambush at
Vella Gulf eleven days before.  Thus when Japanese lookouts spotted American ships at 0029 hours (just as American radar picked up the Japanese) both destroyer groups were steaming in the same direction about 20,000 yards apart with the Japanese northeast of the Americans.

At this time the convoy was heading east, southeast about sixteen miles from its destination, nearer the American than its own escort.  As Ijuin hastened to reform his line for combat, Ryan turned from northeast to west, directly toward the convoy.   Ijuin feared a slaughter, but apparently Ryan had prey bigger than barges in his sights.  He believed he was undetected and wanted to catch the Japanese destroyers in a surprise torpedo attack (Vella Gulf was large in the minds of both
commanders).  This hope was put to rest at 0040 when a Japanese scout plane illuminated the American destroyers with flares.  At this point the Americans were 15,000 yards west of the convoy.  The Japanese destroyers were on an almost parallel course to the northeast, about the same distance away.   Ijuin, expecting Ryan to continue on course for the convoy ordered a torpedo attack.  At 0046 Shigure fired from 12,500 yards; at 0050 Hamakaze did the same, followed by Isokaze at 0051 and Sazanami at 0055.   A total of 31 torpedoes were speeding toward the American destroyers.   Ryan neatly, if unintentionally, frustrated this
attack by sailing around the convoy with a simultaneous turn northwest at 0050 and then north at 0053.

The Japanese force was operating as two groups: Hamakaze and Sazanami, leading by about 6,000 yards turned south at 0055 and opened fire at 0056. Isokaze and Shigure made their turn south about two minutes laterfrom a point 2,000 yards east and thus were closer to the Americans during this part of the action.  Ryan came back to the west at 0056, suffering the Japanese to cross his T.  He was taking a chance: the moon silhouetted his ships, but the Japanese gunnery was not accurate.  Chevalier fired four torpedoes from 9,000 yards at 0058 as the Americans turned north and returned fire.  At 0100 a near miss inflicted minor damage on Hamakaze.  The lead Japanese group turned northwest at this point.  With the range down to 5,500 yards, Shigure fired torpedoes at 0100 and turned away to the northwest as well.  The Americans continued north.  The range was opening as the two rear destroyers traded salvos with the Americans.  At 0111 the two forces came to a parallel course to the northwest almost 15,000 yards apart.  More torpedoes were fired by Isokaze at 0111 while she suffered one hit in return three minutes later.   Hamakaze's radarman believed he detected a powerful American force approaching.  On this basis, Ijuin ordered his ships to continue sailing northwest at speed, effectively retiring from the action.  He believed he had sunk one destroyer.  Ryan gave chase until 0121 when he turned back to the southeast to have a go at the convoy (in this instance, a target of far greater significance than the four destroyers).

The convoy had sensibly scattered during the forty minute destroyer action, and most found refuge on the north coast of Vella Lavella.  Ryan's ships claimed two subschasers, two motor torpedo boats and one Daihatsu.   The Japanese acknowledged the loss of two small subchasers,  Cha5 and Cha12 (135 tons standard, their only armament other than depth charges was a pair of 13.2mm machine guns) and two barges.   The bulk of the Japanese force avoided harm and the staging base was successfully established the next day.

Neither the Americans nor the Japanese were particularly satisfied with the way fought this battle.  Morison asserts the Japanese had a five knot advantage in speed and so it was impossible for Ryan to chase them down.  Hara maintains that the best Japanese speed was two knots slower than the American's and that the Japanese fled only because of the mistaken radar reading. Ryan lightly damaged two of the Japanese destroyers, but they were both in action three days later.  More
significantly, Ryan let pass the opportunity to shoot up an important convoy.  9,000 Japanese troops were subsequently rescued from Kolombangara largely because of this failure.  The Japanese met their strategic objectives and thus, must be considered the victors in this battle.