He served for 28 years as a lawyer in the Army. From 1997 to 2001, he was the Deputy Judge Advocate General of the Army. Altenburg retired at the rank of Major General. His service was marked by extensive experience in military justice, international law and operations law. He was one of several key JAG Corps leaders who helped transform the practice of law in the Army by insisting that lawyers acquire soldier skills and immerse themselves in their clients' business to become more effective advocates.