Lieutenant Colonel Brian Riordan graduated from St. Bonaventure University in 1997 with a Master of Science degree in Education. He was commissioned a Second Lieutenant in December 1997. Upon completion of The Basic School, he was designated an Infantry Officer. Following Infantry Officer’s Course, Second Lieutenant Riordan was assigned to 2nd Battalion, 6th Marines in Camp Lejeune, North Carolina.
In 1999, Lieutenant Riordan deployed with the 24th Marine Expeditionary Unit serving as a Rifle Platoon Commander in Company E during peace keeping operations in Kosovo. Upon their return, he was assigned as Executive Officer, Company E. In 2000, he received orders as the Operation Officer, Range Control, Marine Corps Base Camp Lejeune.
In 2002, Captain Riordan executed orders to Marine Corps Recruit Depot, Parris Island, South Carolina. He served as a Series Commander for four cycles with Company M. In 2003, Captain Riordan became the Aide-de-Camp for the Commanding General of Parris Island and the Eastern Recruiting Region. In 2004, he deployed to Iraq serving as the Personal Security Officer for the General-in-Charge of the Iraq Survey Group.
Following this deployment, Captain Riordan reported to 2nd Battalion, 5th Marines in Camp Pendleton, California in 2005. He commanded Company E, deploying with the 31st Marine Expeditionary Unit. Upon his return, Captain Riordan left active duty.
After a break in service, in 2010, Captain Riordan joined Company F, 4th Light Armored Reconnaissance. During his tenure there, Company F participated in African Lion in Morocco. In 2013, Major Riordan joined Headquarters and Service Company, 4th Light Armored Reconnaissance and served as the Assistant Operations Officer, Operations Officer, and Battalion Executive Officer.
In 2015, Major Riordan deployed to CENTCOM Forward Jordan serving as the Host Nation Coordination Cell Officer in Charge. Upon his return, he joined 3rd Civil Affairs Group serving as the Operations Officer for the G9, III Marine Expeditionary Force.
In 2017, Major Riordan joined 2nd Battalion, 25th Marines serving as the Battalion Executive Officer. In 2019, Lieutenant Colonel joined Marine Corps Civil-Military Operation School as an instructor.
Lieutenant Colonel Riordan is a graduate of Armor Captains Career Course, Light Armored Reconnaissance Leaders Course, Marine Corps Civil-Military Operations Course, and Marine Corps Command and Staff College (non-resident).
Lieutenant Colonel Riordan's personal awards include the Joint Commendation Medal, Navy Commendation Medal, and the Navy and Marine Corps Achievement Medal.