ブーゲンビル島沖海戦
Merrill was Professor of Naval Science and Tactics at Tulane University, until being assigned command of the battleship in April 1942. After promotion to rear admiral in January 1943, Merrill would lead a cruiser-destroyer task force participating in the Battle of Guadalcanal and would later win distinction during the Bougainville campaign at the Battle of Empress Augusta Bay successfully defending ground forces against an assault by the Japanese fleet in a hard-fought night battle. In March 1943, during the Solomon Island campaign, he would show the usefulness of radar against enemy naval forces at the Battle of Blackett Strait. Merrill, commanding Task Force 68, engaged and destroyed two Japanese destroyers and , using only radar fire control. For his efforts he received both the Legion of Merit and the Navy Cross.