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Fortress (chess)
Chess tactic
This article is about a defensive technique in chess. For the chess variant, see Fortress chess.
In chess, the fortress is an endgame drawing technique in which the side behind in material sets up a zone of protection around their king that cannot be penetrated by the opponent. This only works when the opponent does not have a passed pawn or cannot create one, unless that pawn can be stopped (e.g. see the opposite-colored bishops example). An elementary fortress is a theoretically drawn (i.e. a book draw) position with reduced material in which a passive defense will maintain the draw (Müller & Pajeken 2008:183).

Fortresses commonly have four characteristics:

Useful pawn breakthroughs are not possible
If the stronger side has pawns, they are firmly blocked
The stronger side’s king cannot penetrate, either because it is cut off or near the edge of the board
Zugzwang positions cannot be forced, because the defender has waiting moves available (de la Villa 2008:23).
Fortresses pose a problem for computer chess: computers fail to recognize fortress-type positions and are unable to achieve the win against them despite claiming a winning advantage (Guid & Bratko 2012:35).

Fortress in a corner

Rook and pawn versus queen

Opposite-colored bishops

Queen versus two minor pieces

Knight versus a rook and pawn

Bishop versus rook and bishop pawn on the sixth rank

Defense perimeter (pawn fortress)

Other examples

A semi-fortress

Positional draw

See also

Notes

References

Last edited 5 months ago by BD2412


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