At the end of January 1943, the Japanese were preparing to evacuate Guadalcanal, but the Americans misinterpreted the increased ship traffic as preparation for another offensive. Admiral William Halsey decided to send in no less than five task forces to cover the relief of the US 2nd Marine Division. Task Force 18, under Rear Admiral Robert C. Giffen, and consisting of two escort carriers, three heavy cruisers, three light cruisers, and eight destroyers was ordered to provide air support for the relief transports.
However, the escort carriers were too slow (18 knots max) to make a scheduled rendezvous, so Giffen left them behind and pushed on at 24 knots, expecting to get air cover from planes at Henderson Field on Guadalcanal once he made the rendezvous. But he was being tracked by Japanese submarines, who passed on TF 18's position to "Betty" torpedo bombers stationed at Munda and Buka.
At about 1900 hours, the bombers made a first pass, launching several torpedos, none of which hit, and strafing the ships. They then dropped flares to mark the position and course of the task force, and at 1930 another run started, this time scoring a crippling hit on Chicago. Giffen changed course at 2000 and took measures to keep the ships from presenting lit-up targets, and by 2015 the bombers were mostly gone.
Louisville (CA-28) took Chicago in tow, the escort carriers moved up to provide combat air patrol, and aircraft of the nearby Enterprise also joined in. The CAP caught most of a flight of 12 "Bettys" going after Chicago on the afternoon of the 30th, but several got through and launched the torpedos that would sink the cruiser. A final flight of Japanese aircraft failed to find any targets, and the battle was over.