The En passant Chess Move – a Chess Move in Passing

En passant is a term that describes a move in the board game of chess, which loosely translated from French, means ‘in the pawn’s passing’ or ‘in passing’. En passant is a particular chess capture move made instantly after a chess player moves his or her pawn 2 squares forward from its starting position, and the opposition’s pawn could’ve captured it as if it had only moved 1 square forward.

In this instance, the opposition’s pawn may, on the next move, capture the pawn in question as if taking it "as it passes" through the 1st square. The pawn’s resulting position would still be the same as if the pawn had only moved 1 square forward and the opposition’s pawn had captured normally. The En passant capture move must be executed on the very next turn, or the chess player loses his or her right to make this move.

The En passant move is the only instance in the game of chess in which one chess piece captures another but does not move to the captured piece’s square. In a 3-fold chess repetition draw, with 2 positions whose pieces are all on the same squares, and where the same player must move, it is considered different if there is a chance to make an en passant capture move in 1 position but not in the other.

In either descriptive or algebraic chess notation, the letters “E.P.” or similar sometimes denotes en passant captures, but such descriptive notation is not always required. In algebraic notation, the chess move is noted as if the captured pawn progressed only 1 square, for example exf6 (or exf6 e.p.) The numbers and letters used would be determined by the square the pawn has moved to.

When looking at the history of chess, it is noted that the allowing of an en passant is 1 of the last large rule changes in European chess that occurred in the fourteenth or fifteenth century. Changes that occurred at roughly the same time were the introduction of the 2-square first move for pawns, the unlimited range for bishops and queens, and castling. The Asian chess variants do not feature any of these moves because they were separated from European chess prior to that period.

The reason behind en passant was to stop the newly added 2 square first move for pawns from allowing players to evade capture by an opposition’s pawn. Particularly, it should still allow pawns on a chess player's 5th rank the chance to capture a pawn on an adjacent file, which progresses 2 squares from its starting square.

In summary, En passant is the chess move that allows a player’s pawn that has just advanced 2 squares to be captured by the opposition’s pawn on the same rank and adjacent file. The pawn is therefore taken as if the opposition pawn had only moved 1 space. It is only ever possible to take en passant on the very next move.