En passant

Animation of 1…d5 and 2.exd6e.p.

A pawn on its fifth rank may capture an enemy pawn on an adjacent file that has moved two squares in a single move, as if the pawn had moved only one square. The conditions are:

• the capturing pawn must be on its fifth rank;
• the captured pawn must be on an adjacent file and must have just moved two squares in a single move (i.e. a double-step move);
• the capture can only be made on the move immediately after the enemy pawn makes the double-step move; otherwise, the right to capture it en passant is lost.

Example of en passant

Black to move a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h The black pawn is on its initial square. If it moves to f6 (marked by ×), the white pawn can capture it.	White to move a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Black moved their pawn forward two squares in a single move from f7 to f5, "passing" f6.	Black to move a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h White captures the pawn en passant, as if it had moved only one square to f6.

En passant is a unique privilege of pawns—other pieces cannot capture en passant. It is the only capture in chess in which the capturing piece does not replace the captured piece on its square.[3]^:463

In either algebraic or descriptive chess notation, en passant captures are sometimes denoted by "e.p." or similar, but such notation is not required. In algebraic notation, the capturing move is written as if the captured pawn advanced only one square; for example, ...bxa3 or ...bxa3e.p. (see beginning illustration).[4]^:216

Allowing the en passant capture, together with the introduction of the two-square first move for pawns, was one of the last major rule changes in European chess, and occurred between 1200 and 1600. Other relatively recent rule changes were castling, the unlimited range for queens and bishops[13]^:14,16,57 (Spanish master Ruy López de Segura gives the rule in his 1561 book Libro de la invencion liberal y arte del juego del axedrez[4]^:108) and a change to the rules on pawn promotion. In most places the en passant rule was adopted at the same time as allowing the pawn to move two squares on its first move, but it was not universally accepted until the Italian rules were changed in 1880.[5]^:124–125

The motivation for en passant was to prevent the newly added two-square first move for pawns from allowing a pawn to evade capture by an enemy pawn.[13]^:16 Asian chess variants, because of their separation from European chess prior to that period, do not feature any of these moves.

The possibility of an en passant capture is relevant to the claim of a draw by threefold repetition. Two positions with the same configuration of pieces, with the same player to move, are for this purpose considered different if there was an opportunity to make an en passant capture in the first position, and that opportunity no longer exists in the second position.[14]^:27

In his book on chess organization and rules, International Arbiter Kenneth Harkness wrote that it is frequently asked if an en passant capture must be made if it is the only legal move.[15]^:49 This point was debated in the 19th century, with some arguing that the right to make an en passant capture is a "privilege" that one cannot be compelled to exercise. In his 1860 book Chess Praxis, Howard Staunton wrote that the en passant capture is mandatory in that instance. The rules of chess were amended to make this clear.[9] Today, it is settled that the player must make that move (or resign). The same is true if an en passant capture is the only move to get out of check.[15]^:49

• Pawn
• Rules of chess

Bibliography

Look up en passant in Wiktionary, the free dictionary.

• Just, Tim; Burg, Daniel B. (2003), U.S. Chess Federation's Official Rules of Chess (5th ed.), McKay, ISBN 0-8129-3559-4
• Winter, Edward (2006), Chess Facts and Fables, McFarland, ISBN 0-7864-2310-2