The 'Battle of Vella Gulf' was fought between US and Japanese naval forces in the Vella Gulf between the islands of Vella Lavella and Kolombangara in the Solomon islands group (6/7 August 1943).

This was the first time that US destroyers had been permitted to operate independently of US cruiser forces during the Pacific War, and in this battle six US destroyers engaged four Japanese destroyers attempting to reinforce the Japanese troops on Kolombangara. The US warships managed to close the Japanese force undetected with the aid of radar and fired torpedoes, sinking three Japanese destroyers without damage to themselves.

After their victory in the 'Battle of Kolombangara' on 13 July, the Japanese had established a powerful garrison of 12,400 men in the area of Vila on the southern tip of Kolombangara island for the purpose of blocking farther 'island hopping' by the US forces, which had taken Guadalcanal in the previous year, as part of the 'Cartwheel' strategic plan to isolate Rabaul, on New Britain island, as this was the main Japanese base for the forces fighting in the Solomon islands group and on New Guinea. Vila was the principal harbour on Kolombangara, and was supplied at night using fast destroyer transport convoys of the type which the US forces dubbed 'Tokyo Express' runs. Three such supply runs were completed successfully on 19 July, 29 July and 1 August.

During the final run, on 1 August, a force of 15 US PT-boats launched an unsuccessful attack, firing between 26 and 30 torpedoes. By 5 August, the Americans were driving toward the Japanese airfield at Munda on New Georgia island, just to the south of Kolombangara, and the Japanese decided to send a fourth transport run of reinforcements to Vila.

On the night of 6/7 August, the Imperial Japanese navy despatched a force of four destroyers under Captain Kaju Sugiura: these were the two 'Kagero' class ships Hagikaze and Arashi and the two 'Shiratsuyu' class ships Kawakaze of Sugiura’s own Destroyer Division 4 and Shigure of Captain Tameichi Hara’s Destroyer Division 27. The four destroyers carried about 950 soldiers and 200 tons of supplies. The Japanese airfield at Munda on New Georgia, which the force at Vila was assigned to reinforce, was on the verge of being captured, and in fact fell later in that day. The Japanese commanders expected that Vila would become the centre of their next line of defence. The Japanese operational plan specified the same approach route through the Vella Gulf as had been used by the three previous successful transport runs over the objections of Hara, who argued that repeating earlier operations was courting disaster.

The US Navy had been forewarned of the Japanese undertaking and despatched Task Group 31.2 of six destroyers (Dunlap, Craven, Maury, Lang, Sterett and Stack) under the command of Commander Frederick Moosbrugger, to intercept the Japanese destroyers. The morale of Moosbrugger’s crews had been significantly boosted by the realisation that at last they would be free of the combat doctrine that required them to stick close to the cruisers. In the forthcoming night action, therefore, they would be free to apply their own tactics.

The US ships established radar contact with the Japanese force at 23.33. Moosbrugger’s battle plan divided his forces into two divisions. Moosbrugger’s own Destroyer Division 12 (Dunlap, Craven and Maury), whose ships retained their full pre-war torpedo batteries of three or four quadruple launchers, was to launch a surprise torpedo attack out of the shadow of Kolombangara island. Meanwhile, Commander Roger Simpson’s Destroyer Division 15 (Lang, Sterett and Stack), whose ships had two quadruple launchers to allow the addition of additional 40-mm anti-aircraft guns, was to cover Moosburger’s division from an overwatch position, turning to cross the course of the Japanese destroyers. The idea was that any attempt by the Japanese to turn into the first division’s torpedo attack would expose their beams to torpedo attack from the second division.

The two divisions could then switch roles if a repeat torpedo attack proved necessary, or alternate roles if they established the presence of transport barges, which could be destroyed by the second division’s extra guns if necessary. Having learned the harsh lessons of nocturnal naval combat with the Japanese in the 'Battle of Kolombangara', the 'Battle of the Kula Gulf' and an earlier PT-boat skirmish, and having finally addressed the technical problems which had plagued their 21-in (533-mm) Mk 15 torpedoes since the beginning of the war, the US destroyers planned not to give away their position with gunfire until their torpedoes had started to strike their targets.

Dunlap, Craven and Maury fired a total of 24 torpedoes in 63 seconds before turning to starboard and withdrawing at high speed, using the mountainous island to their east to help cover their movements. The US ships were operating on the assumption that the Japanese had nothing to match the new American SG centimetric radar: they knew that their older metric-band radars could not differentiate between surface ships and a land mass, and presumed that Japanese radars were no better. In the event, none of the Japanese ships present actually had radar and the looming mass of the island served to conceal the US ships from visual observation. Lang, Sterett and Stack turned to port to cross their opponent’s 'T' and opened fire as soon as the torpedoes started detonating. All four Japanese destroyers were hit by torpedoes. Hagikaze, Arashi and Kawakaze caught fire and either sank immediately or were quickly sunk by gunfire. The torpedo which struck Shigure failed to detonate and passed through her rudder, allowing her to escape into the darkness. Shigure fired eight torpedoes while retreating from the scene, but all of these missed their targets.

Many of the Japanese soldiers and sailors left floating in the water after their ships sank refused rescue by the US ships. Thus 1,210 Japanese soldiers and sailors were lost, mostly by drowning, some 685 of those lost being soldiers. In addition, 356 men were lost on Hagikaze and Arashi (178 men on each), while 169 men were lost on Kawakaze. A small group of 300 survivors reached Vella Lavella, and these men were later transferred to Kolombangara island. Not one US ship was struck by so much as a single bullet or shell, the only casualty being a crush injury to a gun loader in an onboard accident.

Taking place less than one month after the night action at the 'Battle of Kolombangara', the 'Battle of Vella Gulf' was the first time that the Japanese had been beaten in a night destroyer action. The US destroyers had accomplished what a squadron of 15 PT-boats could not achieve only slightly earlier: sink a 'Tokyo Express' run with torpedoes at the cost of no US naval losses. Japan could no longer supply the garrison on Kolombangara island, which the Allies bypassed, landing instead on Vella Lavella to the west on 15 August. The Japanese army soon abandoned Kolombangara, completing a withdrawal by a time early in October.