McMichael enlisted in the United States Marine Corps on 27 August 1970, and attended recruit training at San Diego, California.

In January 1979, he received orders to Marine Security Guard School and, upon completion of the training, was assigned to the American embassy in Copenhagen, Denmark.

In December 1984, after completing the Staff Noncommissioned Officers Academy Advanced Course, he was transferred to Okinawa, Japan, to serve as the first sergeant of Company C, 3rd Reconnaissance Battalion.

From January 1997 to June 1999, he served as the sergeant major for Manpower and Reserve Affairs Division, Headquarters Marine Corps.

McMichael served in this role from June 2003 until July 17, 2006, when he was succeeded by Army Command Sergeant Major Michael Bartelle.

McMichael sits on the steering committee of the National Symposium for the Needs of Young Veterans, hosted by AMVETS.