Colonel Coss  was commissioned an Infantry Officer upon graduation from Officer Candidate School Class 3-84, 1 June 1984. His first duty assignment was as Rifle Platoon Leader, Bravo Company, 1-38th Infantry, Camp Hovey, South Korea. | His subsequent duty assignments include: Weapons Platoon Leader, Alpha Company, 2-75th Ranger Regiment, Fort Lewis, Washington; Company Executive Officer, Alpha Company, 2-75th Ranger Regiment, Fort Lewis, Washington; Battalion S4, 4-23rd Infantry, Fort Lewis, Washington; Battalion S1, 3-14th, Fort Drum, New York; Company Commander, 3-14th Infantry, Fort Drum, New York; Aide-de-Camp, 10th Mountain Division (Light Infantry), Fort Drum, New York; Infantry Assignment Officer, USA Total Perscom, Alexandria, Virginia; War Plans Officer, D.C.S for Operations and Plans, Pentagon, Virginia; Battalion S3, 4-31st Infantry, Fort Drum, New York; Brigade S3, 2nd Brigade, 10th Mountain Division (Light Infantry), Fort Drum, New York; Operations/Plans Officer J3, USA OJCS, Pentagon, Virginia; Battalion Commander, 1-14th Infantry, Schofield Barracks, Hawaii; Concepts Team Chief, D.C.S for Operations, Pentagon, Virginia; Division G3, 10th Mountain Division (Light Infantry), Fort Drum, New York. | His military awards include: Defense Meritorious Service Medal w/ Oak Leaf Cluster), Meritorious Service Medal (with 4 Oak Leaf Clusters), Joint Service Commendation (with Oak Leaf Cluster), Army Commendation Medal (with 3 Oak Leaf Cluster, Army Achievement Medal w/ 5 Oak Leaf  Clusters, Joint Meritorious Unit Award, Army Good Conduct Award, National Defense Service Medal w/ Oak Leaf Cluster, Armed Forces Expeditionary Medal, Global War on Terrorism Service Medal, Korean Defense Service Medal, Humanitarian Service Medal w/ One Oak Leaf Cluster, Army Service Ribbon, Overseas Service Ribbon w/ Oak Leaf Cluste), NATO Medal.