First recorded by Paper Lace (US #96/UK #1 1974).
Other hit version by Bo Donaldson & the Heywoods (US #1 1974).
From the wiki: “‘Billy, Don’t Be a Hero’ was written by two British song writers Mitch Murray and Peter Callander, was first a hit in the UK for Paper Lace (‘The Night Chicago Died’); some months later it was covered in the US by Bo Donaldson & the Heywoods who scored a #1 hit on the Billboard Hot 100.
“In the song, a young woman is distraught that her fiancé chooses to leave the area with Army recruiters and go with them to fight. Because the song was released in 1974, it was associated by some listeners with the Vietnam War, though it actually does not reference a specific ‘war’.”
Bo Donaldson & the Heywoods, “Billy, Don’t Be a Hero” (1974):