Mullinnix commanded "Saratoga" from April 1943, until August 22, when he was transferred to duty with a carrier division. On November 24, Rear Admiral Mullinnix was on board his flagship (under the command of Captain Irving Wiltsie) commanding Carrier Division 24 and Task Group 52.3 (Air Support Group of Northern Attack Force (Makin)-Task Group 52) when the escort carrier/flagship which had just participated in the Battle of Makin was torpedoed by a Japanese submarine and sunk off Makin Island, in the Gilbert Islands. Declared dead a year later, he was posthumously awarded the Legion of Merit: