He attended Duke University and served in the United States Navy Reserve.
From 1955-1957 he held the title of crypto security officer on the USS Wiltsie.
He later held the positions of fellow at the Institute of Early American History and Culture, assistant professor of history at Occidental College, and Harris Masterson, Jr.
[3][4] During his long teaching career, Gruber published several works on the theme of American military history, specifically regarding the American Revolution.
Another book, The Howe Brothers and the American Revolution, discusses the failure of the Howe Brothers to restore the British government in America.