Private James L. Horr enlisted in the Marine Corps in December 1998 and completed recruit training at MCRD Parris Island, South Carolina. Upon completion of recruit training he was meritoriously promoted to the rank of Private first Class. After completing Marine Combat Training (MCT) in Camp Geiger, he was reassigned to NAS Pensacola, to attend the Avionics technician Course. Upon completion he received the MOS 6483, Deceptive Electronic Countermeasures Technician.
In December 1999, Lance Corporal Horr reported to Marine Aviation Logistics Squadron (MALS) 36, Okinawa, Japan, where he served as an avionics technician and work center supervisor, deploying with the 31st MEU on multiple occasions. In March of 2001 he was meritoriously promoted to the rank of Corporal.
In September 2003, Sergeant Horr reported to Marine Security Guard School in Quantico Virginia. Upon completion he was assigned to the American Embassy in Asuncion, Paraguay. In April 2005 he was transferred to the American Embassy in Bogota, Colombia where he served as the Assistant Detachment Commander and was promoted to the rank of Staff Sergeant in May 2005.
In April 2006, Staff Sergeant Horr reported to MALS-24, MCB Hawaii. During his tour he served as work center supervisor, production control chief, and completed deployments to both OIF and OEF. He was promoted to the rank of Gunnery Sergeant in September 2009.
In January 2010, Gunnery Sergeant Horr reported to the Center for Naval Aviation Technical Training (CNATT), MCAS Cherry Point, NC. While at CNATT he served as the Avionics lead instructor and the Squadron Gunnery Sergeant
In December 2012, he was promoted to the rank of First Sergeant and transferred to 1st Intelligence Battalion, Camp Pendleton, CA. During his tour he served as the Counter Intelligence/Human Intelligence Company First Sergeant and Headquarters and Services Company First Sergeant. He also completed a deployment, in support of OEF, as the Brigade Headquarters Group Afghanistan, Sergeant Major.
In February 2015, First Sergeant Horr reported to 2D Battalion 1st Marines, where he served as the Echo Company First sergeant and completed a deployment with BLT 2/1 as part of the 13th Marine Expeditionary Unit.
In February 2017, First Sergeant Horr reported to Combat Logistics Battalion 5 where he served as the Transportation Services Company First Sergeant. In July 2017 he became the Combat Logistics Battalion 5 Sergeant Major.
In June 2019 he assumed his current billet as the 1st Reconnaissance Battalion Sergeant Major.