Charles O’Toole entered military service as an Army Health Professions Scholarship Program recipient in 1973 while attending medical school at the Texas College of Osteopathic Medicine. On completion of post-graduate medical education, he entered active duty with the Army, serving in numerous positions including Chief of Internal Medicine, Chief of ICU and Chief of Major Medicine/Emergency Medicine Residency Training Program. From 1989 to 1992 he had the unique distinction of holding an officer commission both with the Air Force Reserve and the Army Reserve. He retired in 2008 as a U.S. Air Force Brigadier General.