 Kirklin's military service began in the 11th Armored Cavalry Regiment, in Fulda, Germany, where from 1988 to 1991, he served as a Platoon Leader, General Supply Officer, and Squadron S4, Combat Support Squadron.After graduating from the Advanced Course, he was assigned to the 5th Infantry Division, at Fort Polk, Louisiana, from 1992 to 1993, as a Class IX Accountable Officer.From 1993 to 1996, he was assigned to the 124th Main Support Battalion, 2nd Armored Division, at Fort Hood, Texas, as the Supply and Services Officer, Support Operations Officer, and later as the Light Maintenance Company Commander.