Fortress (chess)
A fortress in the game of chess is a position in which one party has set up its inferior forces in such a way that the opposing party can neither force mate nor a settlement in a won final . With the help of a fortress, a materially inferior party achieves a draw .
The Russian chess trainer Mark Dvoretski defines a fortress as an "impregnable position in which one is limited to passive defense". Occasionally, an exact move may be necessary. Fortress building is an important defense method in the endgame.
Examples
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In this example, Black has a material advantage of one rook against two pawns, but cannot win because his king cannot intervene and White controls the rook's intrusion squares on the h-file.
1.… Rh8 – h3
2. Kg1 – g2! Rh3 – h6
3. Kg2 – g1! A draw , because the black king is reliably shielded by the two white pawns, and the rook alone cannot penetrate.
Belgium 1970
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In this position from a game Arshak Petrosian - Laszlo Hazai, Black is losing. White has the simple maneuver Qb2 – d2, Ka2 – b3, Sa4 – c3, Kb3 – a4, Nc3 – a2 – c1 – b3, after which White would conquer Ba5 and then win easily. Hazai found the ingenious move 1.… Qa7 – b6 !? who set one last trap into which Petrosyan fell. He took 2.Na4xb6 +? the queen because he believed that after 2.… c7xb6 he could avoid the fortress threatened by h5 – h4 with the pawn sacrifice 3. h3 – h4 . But after 3.… g5xh4 Black sacrificed the pawn on the next move with 4.… h4 – h3 , and after 5. g2xh3 h5 – h4 every opportunity to break in was blocked.
Wijk aan Zee 2019
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Anish Giri had blocked the black pawn with his last move 45. b6. Now he threatened to win the black knight after 46. Kg4. With no way of preventing this, Samuel Shankland, to the surprise of Giris , gave up. Shankland had overlooked the fact that he had already built a fortress. To win, the white king would have to go to c7 or c8 to capture the black pawn. However, this can be prevented permanently by the black king, whom White cannot drive from the c8-square. However, if White lets the black king escape after a8, the game ends as soon as White attacks the pawn on b7 with his king. Consequently, Shankland's abandonment was an extremely gross mistake and cost him a sure draw.
Further examples:
- Following the famous combination in the game Tylkowski - Wojciechowski, Poznań in 1931 , White may only have to lose because he failed to build a fortress starting with 37. Rb3.
- See also: The Wrong Runner
Frequent forts
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In Diagram 1, White simply swings with the rook between f3 and h3 , or with the king between g1 , h1 and h2 . In no case can the black king exceed the 3rd row. If the king were on e2 instead of e4 , he could never cross the f-file.
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In Diagram 2 , Black can never permanently enter the squares f1 , f2 , f3 , g3 , h3 with the king . If the white king is forced on g1 or h2, the bishop can move between h1 and g2 .
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In Diagram 3, White simply swings with the king between g1 and h1 . If Black places the bishop on f3 , it can only be captured if White's king is on g1 , because after Kxf3 White creates the opposition with the move Kf1 and holds it in a draw.
Active fortresses
A fortress usually consists of a small area of the chessboard that is held by the weaker side, or the stronger side cannot break through a pawn wall. Amazingly, however, figures who appear offensive can also build fortresses.
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The black king is locked up and completely immobile. Without it, the queen cannot checkmate, and sacrificing her to a knight results in a tie ending. The only possible attempt to win would be that Black locks up the white king with the queen, puts White in a tight spot and the knights have to part with a loss. But this would only work on the squares f7 or g6, both of which are controlled by the knight e5. Therefore the position is a draw.
Problems for chess computers and chess programs
Since fortresses do not represent a definitive end of the game (such as stalemate ) and one side is materially permanently superior, chess computers and chess programs are usually not able to recognize a fortress as such with their normal evaluation methods. Corresponding skills must be programmed into them separately.
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After 1. Qe7xc7 + Kb7xc7 2. b2 – b4! White built a fortress. It doesn't matter whether Black swaps on b4, moves the pawn to c4 or lets him stand on c5 - the black pawns cannot get past the white king, and his black counterpart is locked out by the white pawns. Shredder 7.04 was not able to recognize this position as a simple draw in 2003.
Individual evidence
- ↑ Mark Dworezki: Secrets of targeted chess training . Edition Olms 1993. ISBN 3-283-00254-1 . P. 49 and p. 113.
- ↑ Tim Krabbé's chess diary, entry 223