Chess: Special Moves (really, I'm not making this up)

Castling

Each player may "castle" only once during a game and when conditions are met. Castling is a special move that lets a player move two pieces at once — the King and one Rook. In castling, the player moves his King two squares to its left or right toward one of his Rooks. At the same time, the Rook involved goes to the square beside the King and toward the center of the board (see illustrations at left). In order to castle, neither the King nor the Rook involved may have moved before. Also, the King may not castle out of check, into check, or through check. Further, there may not be pieces of either color between the King and the Rook involved in castling.

Castling is often a very important move because it allows you to place your King in a safe location and also allows the Rook to become more active.

When the move is legal, each player has the choice of castling Kingside or Queenside or not at all, no matter what the other player chooses to do.




En Passant

This French phrase is used for a special pawn capture. It means "in passing," and it occurs when one player moves a pawn two squares forward to try to avoid capture by the opponent's pawn. The capture is made exactly as if the player had moved the pawn only one square forward.



In the diagram, the Black pawn moves up two squares to the square with the dot. On its turn the White pawn may capture the Black one on the square marked with the X. If the White player does not exercise this option immediately — before playing some other move — the Black pawn is safe from "en passant" capture for the rest of the game. But new opportunities may arise for each pawn in similar circumstances.