Custer's notable career in the U.S. Army during the Civil War--he made brigadier general at the age of 23--was largely forgotten after an unfortunate leadership decision in May 1876.
The Battle of Little Bighorn was-- ummm, memorialized in a novelty song by Larry Verne that inexplicably reached number one in 1960. A nervous soldier whines, "Please, Mister Custer, I don't want to go." Lyrics here. You can hear the song here, courtesy of the archives of WFMU, the world's best radio station. (Click on "listen to this show"; the song starts at 33:00.)