Lieutenant Colonel William Thomas Bayha was commissioned as an Infantry Officer upon graduation from Infantry Officer Candidate School class 4-59 at Fort Benning, Georgia on 7 October, 1959. His first duty assignment was as a Platoon Leader, Company C, 1st Battle Group, 35th Infantry, Schofield Barracks, Hawaii.

His subsequent duty assignments were: Executive Officer, Team A, 1st Special Forces Group, Okinawa and Laos; Team B Intelligence Officer, 1st Special Forces Group, Vietnam; Commanding Officer, Team A, 1st Special Forces Group, Vietnam; Company Commander, 3rd Training Brigade, Fort Knox, Kentucky; Battalion Executive Officer, 3rd Training Brigade, Fort Knox, Kentucky; Commanding Officer, Team B, 1st Special Forces Group, Okinawa, Japan; Operations Officer, Operation 35, Studies and Observations Group, Vietnam; Operations Officer, Headquarters, United States Army Ryukyus, Okinawa, Japan; and Advisor to the Philippine Army, Manila, Philippines. His last duty assignment was served as a Military Attaché, United States Embassy, Tokyo, Japan.

His military education includes: Armor Career Course; Command and General Staff College; Defense Language Institute, Chinese and Japanese; and Defense Intelligence School.

His highest military awards and decorations include: Bronze Star Medal (3rd Award), Purple Heart, Defense Meritorious Service Medal, Meritorious Service Medal, Joint Service Commendation Medal (2nd Award), and Combat Infantryman Badge.