Lieutenant Colonel Cothern enlisted in the Marine Corps Reserve in 1998 and served six years with TOW PLT, 23rd Marines, as an 0352 TOW gunner. While in the reserves he attended Southeastern Louisiana University, completed the Platoon Leaders Class in 2003, and graduated with a Bachelor of Arts in Criminal Justice in December 2003. Second Lieutenant Cothern was commissioned in January 2004 and reported to The Basic School in Quantico, VA. Upon completion, Second Lieutenant Cothern underwent Naval Aviation training in Pensacola, FL and was designated a Naval Aviator in August 2006.

First Lieutenant Cothern reported to HMLA/T-303 aboard Camp Pendleton, CA for training in the AH-1W. After completing training, he was assigned to Marine Light Attack Helicopter Squadron-167 at MCAS New River in March 2007. Shortly after check-in, First Lieutenant Cothern was attached to HMM-365(REIN) and deployed to Kandahar, Afghanistan with the 24th MEU in support of Operation Enduring Freedom.  During this deployment he was assigned as the Embark Officer and achieved his Attack Helicopter Commander designation.  After returning from deployment, Captain Cothern transferred to HMLA-467 and was assigned as the ground safety officer, NATOPS Officer, and Aviation Safety Officer before being selected to attend WTI 1-11 in September 2010. 

Captain Cothern was attached to HMM-265(REIN) in June 2011 where he served as the AH-1W Detachment Weapons and Tactics Instructor and Pilot Training Officer for the 31st MEU during its deployment to the Pacific Command AOR. His flight qualifications included Forward Air Controller (Airborne) Instructor, Division Lead, Flight Lead, Flight Leadership Standardization Evaluator, Defensive Air Combat Maneuvering Instructor, and Air Mission Commander.

In July 2012, Captain Cothern executed orders to Expeditionary Warfare School in Quantico, VA. During this time he applied for and was accepted to Marine Helicopter Squadron One (HMX-1), where he reported for duty in May 2013. While at HMX-1, Major Cothern served as the ground safety officer, schedule writer, VH-60 Programs Officer, and NATOPS Officer and served as the unit’s Crew Resource Management Instructor. During his tour at HMX-1 Major Cothern completed the Command and Staff Distance Education Program. Major Cothern was qualified on the CH-46, VH-3D, and VH-60N and served as a White House Helicopter Aircraft Commander, flying missions for the President, Vice-President, and Heads of State.

In May 2017 Major Cothern reported to the Commanding Officer, 24th MEU, as the Air Officer. While serving at the MEU, Major Cothern deployed to the Fifth Fleet AOR, conducted DSCA in Puerto Rico in response to Hurricane Maria, and participated in Exercise Trident Juncture. Major Cothern attended EWTGLANT’s Tactical Air Control Party course in January 2018, graduated as the Honor Graduate, and attended Weapons and Tactics Instructor Course-AOD 2-18, also graduating with honors.

Major Cothern reported to MAG-29 in May 2019 and served as the Personnel Support Detachment Commanding Officer prior to being assigned as the Executive Officer of HMLA-167. In June 2020, LtCol Cothern was again assigned to the 24th MEU as the Executive Officer. LtCol Cothern has accumulated more than 1900 mishap free flight hours in multiple aircraft. His personal decorations include the Meritorious Service Medal with gold star, Navy-Marine Corps Commendation Medal with gold star, two Air Medals – Individual Award with combat “V”, and two Air Medal – Strike/Flight Awards.