 McCain 's father and paternal grandfather eventually became Navy admirals , and were the first father – son pair to achieve four @-@ star admiral rank . His grandfather , Admiral John S. " Slew " McCain , Sr. ( 1884 – 1945 ) , was a pioneer of aircraft carrier operations who in 1942 commanded all land @-@ based air operations in support of the Guadalcanal Campaign , and who ultimately in 1944 – 1945 aggressively led the Fast Carrier Task Force in the Pacific Ocean theater of World War II . His operations off the Philippines and Okinawa , and air strikes against Formosa and the Japanese home islands , caused tremendous destruction of Japanese naval and air forces in the closing period of the war . His death four days after the Japanese surrender ceremony in Tokyo Bay was front page news . Jack McCain was a submarine commander in several theaters of operation in World War II and was decorated with both the Silver Star and Bronze Star . 
