At the conclusion of the war, Guthrie moved to Portsmouth, Virginia, where, later in the year, he became the first Confederate States Navy officer who had resigned from the U.S. Navy, to be pardoned by President Andrew Johnson and had his "disabilities" restored by act of Congress. (I'm not exactly sure what the "disabilities" here means.)
President U.S. Grant appointed Guthrie paymaster and superintendent of the Life Saving Service's lifesaving stations between Cape Henry and Cape Hatteras.
He died a hero when he was drowned while attempting to rescue crewmen from the steamer USS Huron, which had run aground off Nag's Head, North Carolina.
By a strange twist of fate, the wreck and his death occurred near the spot where Guthrie's maternal grandfather, Captain William MacDaniel, had perished years before.