As the Japanese ships withdrew through the Kula Gulf after landing their cargo, they encountered Task Force 68 (TF 68), consisting of three light cruisers (, , and ) and three destroyers (, , and ) commanded by Rear Admiral Aaron S. Merrill. This force was en route to commence bombarding Japanese positions at Vila. Two submarines, "Grayback" and "Grampus", had been assigned to support Merrill's force, and were stationed along likely Japanese withdrawal routes out of the Kula Gulf. Merrill's attack on Vila was timed to coincide with another attack on Munda by four destroyers under Captain Robert Briscoe.