Bryon was commissioned in the United States Marine Corps as a second lieutenant in 1963 after graduation from University of Miami. He graduated from The Basic School at Marine Corps Base Quantico and served as Infantry Platoon Leader with 1st Battalion, 3rd Marines. Byron deployed to Vietnam in 1965. Byron was awarded the Silver Star Medal for valorous actions on 1 July 1965. Byron served a second tour in Vietnam in 1967 as rifle company commander. Byron later attended Amphibious Warfare School, and the Armed Forces Staff College. As a lieutenant colonel, Byron assumed command of 3rd Battalion, 4th Marines in 1978. Byron was promoted to colonel in 1984. Byron assumed command of 2nd Marines from Col. Harry W. Jenkins Jr. on June 9, 1986. Byron relinquished command to Colonel John W. Ripley on July 13, 1988.
His numerous staff assignments include director, InterAmerican Region (International Security Affairs), Office of the Secretary of Defense; the assistant to the Under Secretary of Defense for Policy, Office of the Secretary of Defense; and director for plans and policy (J-5) for the United States Atlantic Command; Branch Head, Western Regional Branch, Plans Division, Plans, Policies and Operations Department, Headquarters Marine Corps from June 1982 to June 1985; and vice director for strategic plans and policy, the Joint Staff, from January 1995 to August 1997. Upon promotion to major general, Byron served as commanding general, 3rd Marine Division from September 2, 1991, to September 1, 1993. His final assignment was United States Military Representative and then as the deputy chairman to the North Atlantic Treaty Organization (NATO) Military Committee, Brussels, Belgium from September 1997 to May 2001. Byron retired in 2001 after 38 years of service.
The President of the United States of America takes pleasure in presenting the Silver Star to First Lieutenant Michael J. Byron (MCSN: 0-88284), United States Marine Corps, for conspicuous gallantry and intrepidity in action while serving as a Platoon Leader with Company A, First Battalion, Third Marines, THIRD Marine Division (Rein.), FMF, in connection with combat operations against the enemy in the Republic of Vietnam on 1 July 1965. While moving to an ambush site during the hours of darkness, the reinforced squad-size patrol suffered heavy casualties from the detonation of an enemy mine. Although injured himself, First Lieutenant Byron refused medical aid until all of his wounded men were treated. Attempted helicopter evacuation was driven off by extremely accurate and intense enemy small arms and automatic weapons fire. With half of his small force having become casualties and realizing the precarious situation he faced, First Lieutenant Byron called for and personally directed the reinforcement of his unit by the remainder of the platoon and other elements of the company. For over two hours, in spite of a disabling wound, he skillfully directed three separate units through terrain occupied by enemy ambush forces, successfully joining these units and subsequently withdrawing his forces to a safe area without incurring further casualties. Having seen to the evacuation of his dead and wounded men, First Lieutenant Byron remained with his men until ordered to be evacuated. By his daring actions and loyal devotion to duty in the face of personal risk, First Lieutenant Byron upheld the highest traditions of the United States Naval Service.