Major General John G. Appel graduated from Rose Polytechnic Institute, Rose-Hulman Institute of Technology, in 1941 with a Bachelor of Science degree in Chemical Engineering. He received a commission as Second Lieutenant in the Chemical Warfare Service Reserve and entered active duty on 7 July 1941.

Among his assignments were Commanding Officer of the U.S. Army Chemical Procurement District in New York City; Chief, Plans and Policy Division, CBR and Nuclear Operations Directorate, and then the Deputy Director, CBR and Nuclear Operations Directorate in the Office of the Assistant Chief of Staff; Director of Plans, Office of the Deputy Chief of Staff for Logistics at the Pentagon; Senior Serving Chemical Officer (1972-1974) and Director of Logistics, J-4 in Germany at the Headquarters, U.S. European Command.

His awards include: The Legion of Merit (2 Oak leaf clusters) and the Army Commendation Medal with one oak leaf cluster.