In April 1944, Ramirez de Arellano as named Commanding Officer of the , thus becoming the first Hispanic submarine commanding officer. He participated in his ship's war patrols 5, 6 and 7. On July 5, 1944, Ramirez de Arellano led the rescue of three downed Navy pilots in the Palau area. On December 4, 1944, the "Balao" departed from Pearl Harbor to patrol in the Yellow Sea. The "Balao" engaged and sunk the Japanese cargo ship "Daigo Maru" on January 8, 1945. Ramirez de Arellano was awarded a Bronze Star with Combat V and a Letter of Commendation.