Kratman enlisted in the U.S. Army in 1974, attended Boston College on an Army scholarship and was commissioned as an officer in 1980. He went on to serve both in the invasion of Panama and the Gulf War. Kratman left active service for law school in 1992, graduating in 1995 after which he practiced law for some years. He was called back for service in 2003 and ended his Army career at the United States Army War College as Director, Rule of Law, for the Peacekeeping and Stability Operations Institute. Kratman retired in 2006 as a lieutenant colonel and became a full-time author. In an autobiography on his website, Kratman gives a personal perspective on his military career, discussing both the Gulf War and many years of deployment to Panama, where he met his wife. Kratman's success as an author has been explained as part of a 21st century turn towards military science fiction writers with first-hand military experience.