During his years at the academy, Masters was active in wrestling club and was in the same class as future marine generals Louis Robertshaw and Paul R. Tyler and Rear Admiral Chester Nimitz Jr.

[1][3][2] Masters was subsequently ordered back to the Marine Corps Base Quantico and appointed Aide-de-Camp to the commanding general, James C. Breckinridge.

He continued in that capacity under Louis M. Little until May 1940, when assumed duties as commanding officer of Marine detachment aboard the cruiser USS Tuscaloosa (CA-37) and took part in Neutrality patrols in the Caribbean and Bermuda.

[1][3][2] Following the Japanese attack on Pearl Harbor, Masters was promoted to the rank of captain in January 1942 and participated in the Russian convoy operations with British Home Fleet in the Norwegian Sea.

Masters also participated in combats against Chinese communist guerillas and assumed duties as executive officer, 5th Marine Regiment in October 1946 and served in that capacity until May 1947.

He was transferred to California in February 1954, when he was appointed assistant chief of staff for operations of Camp Pendleton under Major General John T. Selden and held that assignment until August 1955.

[1][3] In August 1957, Masters was ordered to Hawaii, where he assumed duty as Inspector, Fleet Marine Force, Pacific under his former superior, Edwin A. Pollock.

Masters remained in that capacity until February 1960, when he relieved retiring Brigadier General James D. Hittle as legislative assistant to the Commandant of the Marine Corps, David M. Shoup.

In this capacity, he was co-responsible for the support of development, production, acquisition, and sustainment of general supply, Mortuary Affairs, subsistences, petroleum and water, material and distribution management during peace and war to provide combat power to the U.S. Marine Corps units.

[1][3][2] He then settled in Beaufort, South Carolina, with his wife, Pauline Sullivan Masters, two houses down from General Edwin A. Pollock and enjoyed a wonderful retirement.

Major General John H. Masters died on October 22, 1987, and is buried at Saint Helenas Episcopal Churchyard in Beaufort, South Carolina.