En Passant

Part of the Fundamentals section of Coddy's Chess journey. Lesson 35 of 41.

One capture in chess makes new players cry "that's illegal!". It is not; it has been in the rules for centuries, and it exists to close a loophole. It is called en passant, French for in passing.

The loophole comes from the double step you already know. When pawns gained the right to sprint two squares from their start, they also gained a sneaky trick: sprinting straight PAST an enemy pawn's diagonal, dodging the capture they would have faced by walking one square at a time:

Black pawn about to double-step from d7 to d5, past the white pawn on e5

White's pawn on e5 guards d6. Black's d-pawn tries to sprint two squares, skipping through the guarded square without stopping.

En passant is the answer: for one move, you may capture the sprinter as if it had stopped on the skipped square. Your pawn steps diagonally onto that square, and the enemy pawn comes off the board:

White may capture the black d-pawn en passant by moving to d6

Black just played d5. White may reply exd6 en passant: the e-pawn captures diagonally onto d6, the square the runner skipped.

After the en passant capture the white pawn stands on d6 and the black pawn is gone

After the capture. The white pawn stands on d6 and the black pawn is gone from d5, exactly as if it had moved one square and been taken.

The fine print is strict. Only a pawn may capture en passant, only a pawn standing right beside the arriving double-stepper, and only immediately. Play any other move first and the chance disappears forever. Now or never.

Try it yourself

Black just double-stepped d7 to d5, sprinting right past your e5 pawn. Capture it en passant: click the square White's pawn lands on.