Fastest possible checkmate by en passant En passant is somewhat of a rare move in chess. Checkmating by en passant, however, is an even rarer occurrence. But suppose both sides had the same goal to help cause a checkmate to their opponent via en passant.
What is the minimum amount of moves needed by both White and Black to give checkmate by en passant?
According to
this page
the shortest known mate by en passant capture is in 5.5 moves
(that is, White mates on move 6), and was published by Benko in
Chess Live &amp; Review in 1976:

[Title "Pal Benko's 5.5 move e.p. helpmate"]
[Fen "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w - - 0 0"] 

1. e4 e5 2. Qh5 Nc6 3. g4 d6 4. g5 Kd7 5. Bh3+ f5 6. gxf6#