Castle & En Passant CR

Castle

Castle is a special move for the king that moves the king to the corner of the chessboard and also activates the rook at the same time. Since it is a special move for the king, the player must move the king first when castling.

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If you have moved either your king or your rook, king can no longer castle. King cannot castle neither when it is in check, nor pass through nor end up on a square that is under attack.

Short castle/ King side castle

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Long castle/ Queen side castle

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En Passant

En Passant is a special move for pawn to take the opponent's pawn in the adjacent file which has just pass it.

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Here is the example. White has a pawn in the 5th rank, and black has a pawn horizontally adjacent to it which has not moved yet.

At this moment, if black plays a two-square advance, then white gets a chance to take en passant on f6

(not on f5). However if white chooses not to take en passant this round, then it can not take it anymore.