Allen served as a pilot in a United States Army Specialized Training Program in 1942, and was an Air Force flight surgeon from 1953 to 1955.

He received the Maryland Medical Association award for outstanding achievements in medicine and civic affairs in 1967.

[4] Allen served on the boards of the YMCA, the Salvation Army, the Community Chest of Anne Arundel County, the Red Cross, the Annapolis Chamber of Commerce and the Annapolis chapter of the American Cancer Society; he was a life member of the NAACP, a member of Alpha Phi Alpha fraternity (Eta Eta Lambda chapter),[5] and a member of the Board of stewards for his church, Mount Moriah A. M. E. Allen first served in the House of Delegates representing Anne Arundel County from 1967 to 1974 and then from 1990 to 1991.

Dr. Allen died of a self-inflicted gunshot wound in Annapolis on February 8, 1991, after being diagnosed with pancreatic cancer.

[7] The text of the memorial reads: "A man of honor...A distinguished career of professional and public service...As a Medical Doctor...As a member of the Maryland State Legislature...As an appointee of The President of the United States, to serve his Country on the National level...And as a caring person who has served his community in so many other ways...To help people in need...To provide opportunity for every citizen..."And to set an example that brings out the very best in us".