In 2000, Lieutenant Colonel Barclay was commissioned an officer in the United States Marine Corps after graduating from Indiana University and completing Officer Candidate Course 174. After completing the Basic School and Infantry officer Course he served with First Battalion, Seventh Marine Regiment in 29 Palms, California from 2001 to 2004.
While there he served as Rifle Platoon Commander, Weapons Platoon Commander, and Weapons Company Executive Officer while deploying to Okinawa as part of the Unit Deployment Program and to Iraq for Operation Iraqi Freedom 1.
From 2004 to 2007 he was assigned duties as Officer Selection Officer for West Lafayette, Indiana, as part of Recruiting Station Indianapolis within the Ninth Marine Corps District. Following this he completed the resident course at Expeditionary Warfare School in 2008 and subsequently completed a summer augment rotation at Officer Candidates School as a Platoon Commander.
From 2008 to 2011 he served with Third Battalion, Fifth Marine Regiment in Camp Pendleton, California. While there he served as India Company Commander and completed a deployment as part of Battalion Landing Team 3/5 of the 31st Marine Expeditionary Unit. He then served as Battalion Operations Officer and deployed to the Sangin District of the Helmand Province in Afghanistan in support of Operation Enduring Freedom 10.2.
From 2011 to 2014 he served at the Basic School in Quantico, Virginia. While there he completed duties as Section Head, Company Commander for two student Officer Companies, and as Deputy Director for Warfighting. During this time he also completed educational requirements for the Command and Staff College Distance Education Program.
From 2014 to 2016 he served with Third Battalion, Seventh Marine Regiment in 29 Palms, California. During this time he served as the Battalion Executive Officer and deployed as part of the Ground Combat Element of the Special Purpose Marine Air Ground Task Force, Crisis Response, Central Command. While deployed he led the Train and Advise mission in the Kingdom of Jordan conducting theater security cooperation duties.
From 2016 to 2019 he was assigned duties at Expeditionary Warfare School in Quantico, Virginia. While there he completed duties as a Faculty Advisor, Deputy Director, and as the Chief Instructor.
Lieutenant Colonel Barclay holds an undergraduate degree in Criminal Justice from Indiana University. His personal awards include the Bronze Star, Meritorious Service Medal Gold Star in lieu of third award, Navy Marine Corps Commendation Medal Gold Start in lieu of second award, and the Combat Action Ribbon.