[7] After graduating high school in 1964, he joined the United States Marine Corps.

[8] Gilchrest was decorated with the Purple Heart, Bronze Star, and Navy Commendation Medal.

[8] He is a member of the American Legion, Veterans of Foreign Wars, and Military Order of the Purple Heart.

[10] While teaching at Kent County High School on the Eastern Shore of Maryland, Gilchrest ran against four-term 1st District Democratic incumbent Roy Dyson in 1988.

Dyson was plagued by allegations of improper contributions from defense contractors,[11] questions about his sexual orientation,[12] and the suicide of his top staffer.

[17] He was also the co-chairman of the Congressional Climate Change Caucus together with Democrat John Olver (MA-1).

"[21] In 1993, Gilchrest was the lone Republican vote in support of a bill that would have created DC Statehood.

[28][29] After Gilchrest's loss in the primary, he broke with his party and endorsed Queen Anne's County State's Attorney Frank Kratovil, the Democratic nominee, in the general election,[30] being quoted as saying, "Let's see, the Republican Party, or my eternal soul?"

On September 18, 2008, Gilchrest made radio comments praising the Democratic Presidential ticket of Barack Obama and Joe Biden, causing some media outlets to claim his endorsement of the Democratic ticket.

[33] Despite the fact that he did not officially endorse Obama, in an October 2 Washington Post article, Gilchrest sharply criticized his own party and their presidential nominee, fellow Vietnam veteran John McCain.