Leepson was educated at Hillside High School in Hillside, New Jersey (Class of 1963) and George Washington University where he received his Bachelor of Arts degree in history in 1967 and his Master of Arts degree in European History in 1971.

His work has appeared in many magazines and newspapers, including The Washington Post, The New York Times, The New York Times Book Review, Chicago Tribune, The Baltimore Sun, and Smithsonian, Preservation, and Military History magazines.

He has been interviewed many times on radio and television, including on The Today Show, CBS This Morning Saturday,[5] CNN, MSNBC, Fox News,[6] The History Channel, The Discovery Channel, PBS-TV's History Detectives, All Things Considered, Talk of the Nation, Studio 360, NPR's Here and Now, To The Point, Morning Edition, The Diane Rehm Show, "Imus in the Morning,"[7] the BBC Newshour, Russian Channel 1 TV (RTV), Irish Radio, and CBC (Canada).

A member of The Authors Guild,[12] he was elected to the Board of Directors[13] of the Biographers International Organization (BIO) in 2013.

He received a 2019 National Society Daughters of the American Revolution History Award Medal.