Colonel Patrick H. Downing was commissioned an Infantry Officer upon graduation from Officer Candidate School as the Leadership Graduate and Honor Graduate on 4 August 1967, Class 45-67. His first duty assignment was as a Company Commander, Headquarters Company, 2nd Battalion, 15th Infantry, 3rd Infantry Division, Germany. | His subsequent commands included: Platoon Leader, and later the Company Commander, A Company (Mechanized), 2nd Battalion, 15 Infantry, 3rd Infantry Division, Germany; Platoon Leader, B Company, 1-5088 , 82nd Airborne Division, Phu Bai, Vietnam; Company Commander, 0 Company (Ranger), 75th Infantry, Phu Loi, Vietnam; Assistant Civil Affairs Officer, Headquarters Company, 5th Special Forces Group, Nha Trang, Vietnam; Instructor, Ranger School, United States Army Infantry School, Fort Benning, Georgia; Company Commander and later served as S-4, 4th Battalion, 20th Infantry, Panama; Assistant G-3 Training Officer, 193rd Infantry Brigade, Panama; Assistant Professor of Military Science, Nicholls State University, Thibodaux, Louisiana; S-3 and later served as the Executive Officer, 3rd Battalion (Motorized), 47th Infantry, Fort Lewis, Washington; S-3, 172nd Light Infantry Brigade, Fort Richardson, Alaska; Battalion Commander, Special Troops Battalion and the Ist Battalion, I 7th Infantry, 6th Infantry Division (Light), Fort Richardson, Alaska; Division Chief, United States Army Special Operations Agency, Office of the Deputy Chief of Staff for Operations and Plans, Pentagon, Washington, D.C.; Brigade Commander, Joint Task Force Bravo, Honduras; Chief of Staff and Deputy Commander for Operations for the United States Army South, Fort Clayton, Panama; Senior Army Advisor, 61 Regional Support Command, Birmingham, Alabama.