The Knight plays and captures alternately on White and Black squares, and only reaches such squares as are nearest to him without being immediately adjacent; his move is as it were composed of two steps, one square in a straight line, and one in an oblique direction. Diagram 2 will illustrate this.[[1]]
[1] I should like to quote my friend Mr. John Hart’s clever definition of the Knight’s move, though it may not be new. If one conceives a Knight as standing on a corner square of a rectangle three squares by two, he is able to move into the corner diagonally opposite.
The pawns only move straight forward, one square at a time, except at their first move, when they have the option of moving two squares. In contrast to the pieces, the pawns do not capture in the way they move. They move straight forward, but they capture diagonally to the right and left, again only one square, and only forward. Therefore a pawn can only capture such pieces or pawns as occupy squares of the same colour as the square on which it stands. If, in moving two squares, a pawn traverses a square on which it could have been captured by a hostile pawn, that pawn has the right to capture it, as if it had moved only one square. This is called capturing en passant. However, this capture can only be effected on the very next move, otherwise the privilege of capturing en passant is lost.
Diag. 2
If a player succeeds in reaching the eighth rank with one of his pawns he is entitled to call for any piece of higher grade, with the exception of the King, in place of such pawn.
Each move in a game of chess consists of the displacement of one piece only, with the exception of what is termed “castling,” in which the King and either Rook can be moved simultaneously by either player once in a game. In castling, the King moves sideways to the next square but one, and the Rook to which the King is moved is placed on the square which the King has skipped over. Castling is only allowed if neither the King nor the Rook concerned have moved before, and if there is no piece between the Rook and King.
Diagram 3 shows a position in which White has castled on the Queen’s side, and Black on the King’s side. Castling is not permitted if the King in castling must pass over a square attacked by a hostile piece. A square (or a piece) is said to be “attacked” when the square (or the piece) is in the line of action of a hostile unit. A square (or a piece) is said to be covered or protected if an opposing piece occupying that square (or capturing the piece) could itself be captured.
When attacking the King it is customary to call “check,” to notify the opponent of the fact; for the attack on the King
