Colonel McCollough was commissioned in 1991 after graduating from Norwich University. After completing The Basic Officers’ Course with honors, he was assigned to the Infantry Officers’ Course. His first posting was to 2d Battalion, 3d Marines.
In 1995, he reported for duty with Fleet Anti-Terrorism Security Team Company where he deployed to the Mid-Atlantic to interdict a foreign freighter during Operation Marathon and to Central Command in support of Operation Desert Thunder and Operation Southern Watch. In 1998 he received orders to Amphibious Warfare School, where he graduated with honors.
He then reported to 3d Battalion, 5th Marines where he served as Weapons Company Commander and Battalion Operations Officer. His subsequent assignment was as the Assistant Operations Officer, G-3, 1st Marine Division.
In 2002, he reported to the Office of Legislative Affairs for duty as a Congressional Fellow. Following the Fellowship, he became the Deputy Marine Liaison to the U.S. House of Representatives.
He reported back to 3d Battalion, 5th Marines for duty as Executive Officer in 2005 and was later assigned as the Team Chief for Military Transition Team 131, during Operation Iraqi Freedom.
In 2006, he was assigned as the Operations Officer, 1st Marine Regiment. He deployed to Iraq with Regimental Combat Team 1 where he served as the Executive Officer and Tribal Engagement Officer.
Upon return from Iraq he assumed command of 1st Battalion, 5th Marines. In 2009 he led the unit in Afghanistan in support of Operation Enduring Freedom where his battalion seized the Nawa District of Helmand Province during Operation Kanjari.
After battalion command he graduated with honors from the Marine Corps War College, and was subsequently posted to the J-3 on the Joint Staff.
In 2013 Colonel McCollough returned to the operating forces and deployed to Afghanistan as the Officer in Charge of the Regional Command (SW) Afghan National Police Advisor Team.
In 2014 he assumed command of 1st Marines and led them overseas in 2015 as the Command Element, Special Purpose Marine Air Ground Task Force – Crisis Response – Central Command in support of Operation Inherent Resolve.
In 2016 he became the Director of the Marine Corps Command and Staff College.
Colonel McCollough’s personal awards include the Legion of Merit with “V” device and two gold stars, the Bronze Star with “V” device, the Purple Heart, and the Combat Action Ribbon with one gold star. He is married with two sons.