Lieutenant General Thomas Horlander was born in Aurora, Colorado and graduated with a Bachelors of Business Administration from Western Washington University. Lieutenant General Horlander holds Masters Degrees from Oklahoma City University, the U.S. Army Command and General Staff College and the U.S. Army War College.

Lieutenant General Horlander was commissioned in 1983 as a second lieutenant of Field Artillery through the Officer Candidate School. His most recent assignment was as 30th Director of the Army Budget (ABO). Prior to that, he served as the Director of Business Operations, Office of Business Transformation, Washington, D.C.; G8, USARCENT/3rd Army forward deployed in the Southwest Asia theater of operations; Director of Resource Management/G8, Installation Management Command; Executive Officer to the Military Deputy, ASA (FM&C); Comptroller/G8, V Corps, U.S. Army Europe and Multi-National Corps, Iraq; Director, Resource Management at the U.S. Army Aviation Center, Fort Rucker, AL; Deputy Secretary for Finance (Comptroller), Inter-American Defense Board, Washington D.C.; Executive Officer, 1st Battalion, 319th Field Artillery (Airborne), 82d Airborne Division, Fort Bragg, NC; Assistant S-3 (Operations), Division Artillery, 82d Airborne Division, Fort Bragg, NC; Budget Course Director and Instructor/Writer, Finance School, U.S. Army Soldier Support Center, Fort Jackson, SC; Aide-de-Camp to Commander, Allied Land Forces Southern Europe, Verona, Italy; Battery Commander, 12th Field Artillery Detachment, 559th U.S. Artillery Group, U.S. Army Europe and Seventh Army, Oderzo, Italy; and various field artillery positions at Fort Sill, Oklahoma and with the 2nd Infantry Division in South Korea. General Horlander is an accomplished linguist, Master Strategist, and has published numerous books and articles.

Lieutenant General Horlander's awards and decorations include the Army Distinguished Service Medal, Defense Superior Service Medal, Legion of Merit (with 2 Oak Leaf Clusters); Bronze Star Medal; Defense Meritorious Service Medal; Meritorious Service Medal (with 3 Oak Leaf Clusters); Joint Service Commendation Medal; Army Commendation Medal (with 3 Oak Leaf Clusters); Joint Service Achievement Medal; Army Achievement Medal; the Senior Parachutist Badge; Italian Airborne Wings, and the Army Staff Identification Badge.

Lieutenant General Horlander assumed duties as the Military Deputy to the Assistant Secretary of the Army (Financial Management & Comptroller) on 3 August 2017.