Major General Donahue was commissioned as a second lieutenant in the Infantry Branch in 1992 from the United States Military Academy at West Point. Major General Donahue served as a platoon leader in Korea, Fort Polk, Louisiana and the 3rd Battalion, 75th Ranger Regiment at Fort Benning, Georgia. Following promotion to captain, he served as a rifle company commander in 5th Battalion, 87th Infantry in Camp Kobbe, Panama.
He then served as an assistant operations officer, rifle and headquarters company commander in 2nd Battalion, 75th Ranger Regiment. Major General Donahue subsequently moved to Washington, D.C. and served as Special Assistant to the Chairman of the Joint Chiefs of Staff. Following his time at the Pentagon, he served as assistant operations officer, squadron operations officer, squadron executive officer, troop commander, selection and training detachment commander, operations officer, squadron commander, and deputy brigade commander (support) within US Army Special Operations Command (USASOC) at Fort Bragg, North Carolina.
After attending Harvard University as a US Army War College Fellow, he returned to Fort Bragg and commanded a brigade within USASOC. He was then assigned as the Director of Operations for the US Joint Special Operations Command (JSOC). He then served as the deputy commanding general (maneuver) of the 4th Infantry Division at Fort Carson, CO where he deployed in support of Operation Atlantic Resolve. Major General Donahue then served as the Infantry School Commandant and Director of the Soldier Lethality Cross Functional Team at Fort Benning, GA.
He then served as the Deputy Director for Special Operations and Counter-Terrorism, J-3, for the Joint Staff in Washington, D.C. He most recently served as the Commander, Special Operations Joint Task Force-Afghanistan in support of Operation Freedom’s Sentinel. He has deployed 17 times in support of operations in Afghanistan, Iraq, Syria, North Africa, and Eastern Europe. His military education includes the Infantry Officer Basic and Advanced Courses, the Naval War College, and the US Army War College Fellowship at Harvard University.