Chess Strategy. Edward Lasker

OF THE GAME

      A GAME of chess is played by two opponents on a square board consisting of sixty-four White and Black squares arranged alternately. The forces on each side comprise sixteen units, namely a King, a Queen, two Rooks, two Bishops, two Knights, and eight Pawns. All units move according to different laws, and the difference in their mobility is the criterion of their relative value and of the fighting power they contribute towards achieving the ultimate aim, namely, the capture of the opposing King. Before I can explain what is meant by the capture of the King, I must set out the rules of the game in full.

      Diagram 1 shows the position the forces take up for the contest. The board is so placed that there is a white square at the top left-hand corner. The Rooks take up their positions at the corner squares, and next to them the Knights. Next to those again are the Bishops, and in the centre the King and Queen, the White Queen on a White square, and the Black Queen on a Black square. The eight pawns occupy the ranks immediately in front of the pieces. From this initial position, White begins the game in which the players must move alternately.

      The pieces move in the following way: The Rook can move from any square it happens to be on, to any other square which it can reach in a straight line, either perpendicularly or horizontally, unless there is another piece of the same colour in the way, in which case it can only move as far as the square immediately in front of that piece. If it is an opposing piece which blocks the way, he can move on to the square that piece occupies, thereby capturing it. The piece thus captured is removed from the board. The Bishop can operate along either of the diagonals of which the square on which he is standing forms part. A Bishop on a White square can there fore never get on to a Black one.

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       8 | #R | #Kt| #B | #Q | #K | #B | #Kt| #R |

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       7 | #P | #P | #P | #P | #P | #P | #P | #P |

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       6 | | | | | | | | |

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       5 | | | | | | | | |

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       4 | | | | | | | | |

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       3 | | | | | | | | |

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       2 | ^P | ^P | ^P | ^P | ^P | ^P | ^P | ^P |

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       1 | ^R | ^Kt| ^B | ^Q | ^K | ^B | ^Kt| ^R |

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       a b c d e f g h

      DIAG. 1.

      The Queen commands both the straight and the oblique lines which start from the square she stands on, and therefore unites the power of both Rook and Bishop in her movements.

      The King has similar powers to the Queen, but curtailed, inasmuch as he can only move one step at a time. He therefore only controls one neighbouring square in any direction.

      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.

      [Footnote: 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.

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       8 | | | | | | | | |

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       6 | | | | * | | * | | |

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       5 | | | * | | | | * | |

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       4 | | | | | ^Kt| | | |

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       3 | | | * | | | | * | |

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       2 | | | | * | | * | | |

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       1 | | | | | | | | |

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       A B C D E F G H

      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

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       8 | | | | #R | | #R | #K | |

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       7 | #P | #P | | | | #P | #P | #P |

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