Callaghan is perhaps best known for ordering, despite disagreement from some of his crew, that an honorable burial at sea be held for an enemy pilot who died during a suicide attack on "Missouri" in 1945. Following World War II, he directed the US Navy's transportation service and filled senior command roles in eastern Asia, including leadership of the US Pacific Fleet's Amphibious Force during the Korean War. He retired from the US Navy at the rank of vice admiral in 1957 and worked in civilian maritime transport before retiring to Maryland.