In Castling, the King must be moved first, or before the Rook is quitted. If the Rook be quitted before the King is touched, the opposing player may demand that the move of the Rook shall stand without the Castling being completed.
Howard StauntonIf, during the course of the game, it be discovered that any error or illegality has been committed in the moves of the pieces, the moves must be retraced, and the necessary correction made, without penalty.
Howard StauntonBe cautious of playing your Queen in front of your King and in subjecting yourself to a discovered check. It is better when check is given to your King to interpose a man that attacks the checking Piece than with one that does not.
Howard Staunton