John Edward Mathis enlisted in the U. S. Navy in February 1951. He attended nine weeks recruit training at San Diego, California. From boot camp, he was assigned to the U. S. Naval schools for mine warfare at Yorktown, Virginia. John completed the elementary course with the class of 9-51, the advanced course with the class of 2-52 and the operational mine servicing course with 3-52. Assigned to Patrol Squadron Seven (VP-7) , they deployed to Japan until December 1954. John was then assigned to the U.S.S. Coral Sea (CVA-43). Following a six-month Mediterranean cruise, John was discharged as a Mineman 2^nd Class in February 1955.

His awards included the National Defense Service Medal, the United Nations Service Medal, the Korean Service Medal, the Navy Occupation Service Medal and the Good Conduct Medal.