In battle these Allied vessels deployed in a single column with five destroyers in the van followed by the light cruisers and then by five destroyers in the rear. Each group of five destroyers formed a squadron. The first of these, designated Destroyer Squadron 21, was commanded by Captain Francis X. McInerney. The second destroyer squadron was Captain Thomas J. Ryan's Destroyer Squadron 12; it had only recently been assigned to Ainworth's task force, as had the New Zealand cruiser which had been assigned to Ainsworth's force following the loss of during the Battle of Kula Gulf on 6 July. Together, the three cruisers were grouped together as Cruiser Division 9. Ainsworth's mission was to prevent Japanese troops and supplies from landing as part of efforts to stem the flow of reinforcements towards Munda.