chess Chess is a board game for two players, called White and Black, each controlling an army of chess pieces in their color, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to dist ...

, a fortress is an

endgame Endgame, Endgames, End Game, End Games, or similar variations may refer to: Film * ''The End of the Game'' (1919 film) * ''The End of the Game'' (1975 film), short documentary U.S. film * ''Endgame'' (1983 film), 1983 Italian post-apocalyptic f ...

drawing technique in which the side behind in sets up a zone of protection that the opponent cannot penetrate. This might involve keeping the enemy king out of one's position, or a zone the enemy cannot force one out of (e.g. see the opposite-colored bishops example). An elementary fortress is a theoretically drawn (i.e. a ) position with reduced material in which a passive defense will maintain the draw. Fortresses commonly have the following characteristics: # Useful

pawn Pawn most often refers to: * Pawn (chess), the weakest and most numerous piece in the game * Pawnbroker or pawnshop, a business that provides loans by taking personal property as collateral Pawn may also refer to: Places * Pawn, Oregon, an his ...

are not possible. # If the stronger side has pawns, they are firmly blocked. # The stronger side's

king King is the title given to a male monarch in a variety of contexts. The female equivalent is queen, which title is also given to the consort of a king. *In the context of prehistory, antiquity and contemporary indigenous peoples, the tit ...

cannot penetrate because it is either cut off or near the edge of the board. #

Zugzwang Zugzwang (German for "compulsion to move", ) is a situation found in chess and other turn-based games wherein one player is put at a disadvantage because of their obligation to make a move; a player is said to be "in zugzwang" when any legal move ...

positions cannot be forced because the defender has available. 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.

Fortress in a corner

Perhaps the most common type of fortress, often seen in endgames with only a few pieces on the board, is where the defending king is able to take refuge in a corner of the board and cannot be forced away or checkmated by the superior side. These two diagrams furnish two classic examples. In both cases, Black simply shuffles their king between a8 and the available square adjacent to a8 (a7, b7, or b8, depending on the position of the white king and pawn). White has no way to dislodge Black's king, and can do no better than a draw by stalemate or some other means. Note that the bishop and

wrong rook pawn In chess endgames with a bishop, a pawn that is a may be the wrong rook pawn. With a single bishop, the result of a position may depend on whether or not the bishop controls the square on the chessboard on which the pawn would promote. Since a ...

ending (i.e. where the pawn is a

rook pawn This glossary of chess explains commonly used terms in chess, in alphabetical order. Some of these terms have their own pages, like ''fork'' and ''pin''. For a list of unorthodox chess pieces, see Fairy chess piece; for a list of terms specific t ...

whose

promotion Promotion may refer to: Marketing * Promotion (marketing), one of the four marketing mix elements, comprising any type of marketing communication used to inform or persuade target audiences of the relative merits of a product, service, brand or i ...

square is the color opposite to that of the bishop) in the diagram is a draw even if the pawn is on the seventh

rank Rank is the relative position, value, worth, complexity, power, importance, authority, level, etc. of a person or object within a ranking, such as: Level or position in a hierarchical organization * Academic rank * Diplomatic rank * Hierarchy * ...

or further back on the a-. Heading for a bishop and wrong rook pawn ending is a fairly common drawing resource available to the inferior side. The

knight A knight is a person granted an honorary title of knighthood by a head of state (including the Pope) or representative for service to the monarch, the church or the country, especially in a military capacity. Knighthood finds origins in the Gr ...

and rook pawn position in the diagram, however, is a draw only if White's pawn is already on the seventh rank, making this drawing resource available to the defender much less frequently. White wins if the pawn is not yet on the seventh rank and is protected by the knight from behind. With the pawn on the seventh rank, Black has a stalemate defense with their king in the corner.

Example game: Serper vs. Nakamura, 2004

A fortress is often achieved by a sacrifice, such as of a piece for a pawn. In the game between Grigory Serper and

Hikaru Nakamura Christopher Hikaru NakamuraU.S. Chess Championship, White would lose after 1.Nd1 Kc4 or 1.Nh1 Be5 or 1.Ng4 Bg7. Instead he played :1. Nxe4! Kxe4 :2. Kf1! Heading for h1. After another 10 moves the position in the following diagram was reached: Black has no way of forcing White's king away from the corner, so he played :12... Kf2 and after 13.h4 gxh4 the game was drawn by stalemate.

Back-rank defense

The back-rank defense in some

rook and pawn versus rook endgame The rook and pawn versus rook endgame is a fundamentally important, widely studied chess endgame. Precise play is usually required in these positions. With optimal play, some complicated wins require sixty moves to either checkmate, capture the ...

s is another type of fortress in a corner (see diagram). The defender perches their king on the pawn's queening square, and keeps their

rook Rook (''Corvus frugilegus'') is a bird of the corvid family. Rook or rooks may also refer to: Games *Rook (chess), a piece in chess *Rook (card game), a trick-taking card game Military * Sukhoi Su-25 or Rook, a close air support aircraft * USS ...

on the back rank (on the "long side" of the king, not, e.g., on h8 in the diagram position) to guard against horizontal checks. If 1.Rg7+ in the diagram position, Black heads into the corner with 1...Kh8! Note that this defense works ''only'' against rook pawns and knight pawns.

Rook vs. bishop

In the ending of a rook versus a bishop, the defender can form a fortress in the "safe" corner—the corner that is not of the color on which the bishop resides (see diagram). White must release the potential stalemate, but they cannot improve their position. :1. Rc3 Ba2 :2. Rc2 Bb3 :3. Rc7 Bg8

Pawn and bishop

In this position from de la Villa, White draws if their king does not leave the corner. It is also a draw if the bishop is on the other color, so it is not a case of the

wrong bishop In a chess endgame, a wrong bishop is a bishop that would have been better placed on the opposite square color; in other words, a bishop is unable to guard squares of the other color. This most commonly occurs with a bishop and one of its , but it ...

Rook and pawn versus queen

In the diagram, Black draws by moving his rook back and forth between the d6- and f6-squares, or moves his king when checked, staying behind the rook and next to the pawn. This fortress works when all of these conditions are met: *The pawn is still on its second . *The pawn is on ''b'' through ''g''. *The pawn is protecting its rook on the third rank. *The opposing king is beyond the defender's third rank. *The defending king protects its pawn. The white king is not able to cross the rank of the black rook, and the white

queen Queen or QUEEN may refer to: Monarchy * Queen regnant, a female monarch of a Kingdom ** List of queens regnant * Queen consort, the wife of a reigning king * Queen dowager, the widow of a king * Queen mother, a queen dowager who is the mother ...

is unable to do anything useful. : 1. Qd5+ Rd6 : 2. Qb5+ Kd8 : 3. Qb8+ Kd7 : 4. Qb5+ ½-½ Positions such as these (when the defending rook and king are near the pawn and the opposing king cannot attack from behind) are drawn when (see diagram): * the pawn is on the c-, d-, e-, or f-file and the second, sixth, or seventh rank * the pawn is anywhere on the b- or g-file * the pawn is on the a- or h-file and the third or seventh rank. Otherwise, the queen wins.

Example from game

In this position, with Black to move, Black can reach a drawing fortress. : 1...b4 : 2. Kd6 Rc3 : 3. Kd7 and now 3...Ka3 and several other moves reach the fortress. In the actual game, Black made the weak move 3...Rd3? and lost.

Similar example

In this 1959 game between Whitaker and Ferriz, White sacrificed a rook for a knight in order to exchange a pair of pawns and reach this position, and announced that it was a draw because (1) the queen cannot mate alone, and (2) the black king and pawn cannot approach to help. However,

endgame tablebase An endgame tablebase is a computerized database that contains precalculated exhaustive analysis of chess endgame positions. It is typically used by a computer chess engine during play, or by a human or computer that is retrospectively analysin ...

analysis shows Black to have a forced win in 19 moves starting with 50... Qc7+ (the only winning move), taking advantage of the fact that the rook is currently unprotected – again illustrating how tablebases are refining traditional endgame theory.

Example with more pawns

From the diagram, in Salov vs. Korchnoi,

Wijk aan Zee Wijk aan Zee ( literally ''Neighborhood at Sea'') is a village on the coast of the North Sea in the municipality of Beverwijk, the province of North Holland of the Netherlands. The prestigious Tata Steel Chess Tournament (formerly called the Corus ...

1997, White was able to hold a draw with a rook versus a queen, even with the sides having an equal number of pawns. He kept his rook on the fifth rank blocking in Black's king, and was careful not to lose his rook to a

fork In cutlery or kitchenware, a fork (from la, furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tine (structural), tines with which one ...

or allow a queen sacrifice for the rook in circumstances where that would win for Black. The players agreed to a draw after: :48. Kg2 Kg6 49. Rh5 Qe2+ 50. Kg3 Qf1 51. Kf4 Qe1 52. Rd5 Qc1+ 53. Kg3 Qc7+ 54. Kg2 Qf4 55. Rh5 Kf6 56. Rd5 Ke6 57. Rh5 Qd2+ 58. Kg3 f6 59. Rf5 Qc1 60. Rh5 Qg1+ 61. Kf4 Qe1 62. Rb5 Qc1+ 63. Kg3 Qg1+ 64. Kf4 Qh2+ 65. Ke3 Kf7 66. Rh5 Qg1+ 67. Kf4 Kg6 68. Rd5 Qh2+ 69. Ke3 Kf7 70. Rh5 Qg1+ 71. Kf4 Ke6 72. Rb5 Qh2+ 73. Ke3 Kd6 74. Rf5 Qb2 75. Rh5 Ke6 76. Kf4 Qc3 77. Kg3 Qc7+ 78. Kg2 Qf7 79. Rb5 Qe8 80. Rf5 Qg6 81. Rb5 ½–½

Opposite-colored bishops

In endings with bishops of opposite colors (i.e. where one player has a bishop that moves on light squares, while the other player's bishop moves on dark squares), it is often possible to establish a fortress, and thus hold a draw, when one player is one, two, or occasionally even three pawns behind. A typical example is seen in the diagram. White, although three pawns behind, has established a drawing fortress, since Black has no way to contest White's stranglehold over the light squares. White simply keeps his bishop on the h3–c8 diagonal.

Example from game

In an endgame with opposite-colored bishops, positional factors may be more important than material. In this position, Black

sacrifices Sacrifice is the offering of material possessions or the lives of animals or humans to a deity as an act of propitiation or worship. Evidence of ritual animal sacrifice has been seen at least since ancient Hebrews and Greeks, and possibly exis ...

a pawn (leaving him three pawns down) to reach a fortress. : 1... Kf5! : 2. Kxf7 Bh5+ : 3. Kg7 Bd1 : 4. Be7 ½-½ After 4...Be2 5.Kh6 Bd1 6.h5 Black just waits by playing 6...Be2.

Queen versus two minor pieces

Here are drawing fortresses with two versus a

. Usually the defending side will not be able to get to one of these positions.

Bishop and knight

The bishop and knight fortress is another type of fortress in a corner. If necessary, the king can move to one of the squares adjacent to the corner, and the bishop can retreat to the corner. This gives the inferior side enough tempo moves to avoid

zugzwang Zugzwang (German for "compulsion to move", ) is a situation found in chess and other turn-based games wherein one player is put at a disadvantage because of their obligation to make a move; a player is said to be "in zugzwang" when any legal move ...

. For example: :1. Kb5 Ka7 :2. Qd8 Ba8 :3. Ka5 Bb7.

Two bishops

In the two bishop versus queen ending, the queen wins if the

Lolli Lolli is an Italian surname. Notable people with the surname include: * Alberto Carlo Lolli (born c.1876), Italian film director of the silent era * Antonio Lolli (1725–1802), Italian violinist and composer * Anthony Lolli, developer and found ...

position is not reached, but some of them take up to seventy-one moves to either checkmate or win a bishop, so the

fifty-move rule The fifty-move rule in chess states that a player can claim a draw if no has been made and no pawn has been moved in the last fifty moves (for this purpose a "move" consists of a player completing a turn followed by the opponent completing a tur ...

comes into play. From the diagram: :1. Qe7+ Kc8 :2. Qe6+ Kb7 :3. Qd6 Ba7 :4. Qe7+ Kb6! :5. Qd8+ Kb7! :6. Ka5 Bc5! and White cannot prevent ... Bb6, which gets back to the Lolli position.

Two knights

In the two knights fortress, the knights are next to each other and their king should be between them and the attacking king. The defender must play accurately, though. There are several drawing positions with two knights against a queen. The best way is to have the knights adjacent to each other on a file or rank, with their king between them and the enemy king. This is not a true fortress since it is not static. The position of the knights may have to change depending on the opponent's moves. In this position (Lolli, 1763), : 1. Qd1 Nd2+ : 2. Ke2 Nb3 and Black has an ideal defensive position. If the knights cannot be adjacent to each other on a file or rank, the second best position is if they are next to each other diagonally (see diagram). The third type of defensive formation is with the knights protecting each other, but this method is more risky.

With pawns

Sometimes the two minor pieces can achieve a fortress against a queen even where there are pawns on the board. In Ree-

Hort Hort may refer to: People * Erik Hort (born 1987), American soccer player * F. J. A. Hort (1828–1892), Irish theologian * Greta Hort (1903–1967), Danish-born literature professor * Josiah Hort (c. 1674–1751), English clergyman of the Chu ...

1986 (first diagram), Black had the material disadvantage of rook and bishop against a queen. Dvoretsky writes that Black would probably lose after the natural 1...Bf2+? 2.Kxf2 Rxh4 because of 3.Kg3 Rh7 4.Kf3, followed by a king march to c6, or 3.Qg7!? Rxf4+ 4.Kg3 Rg4+ 5.Kf3, threatening 6.Qf6 or 6.Qc7. Instead, Hort forced a draw with 1... Rxh4!! 2. Kxh4 Bd4! (imprisoning White's queen) 3. Kg3 Ke7 4.Kf3 Ba1 (second diagram), and the players agreed to a draw. White's queen has no moves, all of Black's pawns are protected, and his bishop will shuttle back and forth on the squares a1, b2, c3, and d4.

Knight versus a rook and pawn

At the great

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1924 tournament, former

world champion A world championship is generally an international competition open to elite competitors from around the world, representing their nations, and winning such an event will be considered the highest or near highest achievement in the sport, game, ...

Emanuel Lasker Emanuel Lasker (; December 24, 1868 – January 11, 1941) was a German chess player, mathematician, and philosopher who was World Chess Champion for 27 years, from 1894 to 1921, the longest reign of any officially recognised World Chess Cham ...

was in trouble against his namesake

Edward Lasker Edward Lasker (born Eduard Lasker) (December 3, 1885 – March 25, 1981) was a German-American chess and Go player. He was awarded the title of International Master of chess by FIDE. Lasker was an engineer by profession, and an author of ...

, but surprised everyone by discovering a new endgame fortress. Despite having only a knight for a rook and pawn, White draws by moving his knight back and forth between b2 and a4. Black's only real winning try is to get his king to c2. However, to do so Black has to move his king so far from the pawn that White can play Ka3–b2 and Nc5xb3, when the rook versus knight ending is an easy draw. The game concluded: :93. Nb2 Ke4 94. Na4 Kd4 95. Nb2 Rf3 96. Na4 Re3 97. Nb2 Ke4 98. Na4 Kf3 99. Ka3! Ke4 If 99...Ke2, 100.Nc5 Kd2 101.Kb2! (101.Nxb3+?? Kc2 and Black wins) and 102.Nxb3 draws. :100. Kb4 Kd4 101. Nb2 Rh3 102. Na4 Kd3 103. Kxb3 Kd4+ ½–½

Bishop versus rook and bishop pawn on the sixth rank

A bishop can make a fortress versus a rook and a

bishop pawn This glossary of chess explains commonly used terms in chess, in alphabetical order. Some of these terms have their own pages, like ''fork'' and '' pin''. For a list of unorthodox chess pieces, see Fairy chess piece; for a list of terms specific ...

on the sixth

, if the bishop is on the color of the pawn's seventh rank square and the defending king is in front of the pawn. In this position, White would win if he had gotten the king to the sixth rank ahead of the pawn. Black draws by keeping the bishop on the diagonal from ''a2'' to ''e6'', except when giving

check Check or cheque, may refer to: Places * Check, Virginia Arts, entertainment, and media * ''Check'' (film), a 2021 Indian Telugu-language film * ''The Checks'' (episode), a 1996 TV episode of ''Seinfeld'' Games and sports * Check (chess), a thr ...

. The bishop keeps the white king off ''e6'' and checks him if he goes to ''g6'', to drive him away. A possible continuation: :1... Ba2 2. Kf4 2.f7 is an interesting attempt, but then Black plays 2...Kg7! and then 3...Bxf7, with a draw. 2...Kg7 prevents 3.Kf6, which would win. :2... Bc4 3. Kg5 Bd5! The only move to draw, since the bishop must be able to check the king if it goes to g6. :4. Rc7 Ba2! 5. Kg6 Bb1+! 6. Kh6 Ba2! 7. Ra7 If 7.f7 Bxf7!: the pawn can be safely when the white king is on h6. :7... Bc4 Draw, because White cannot make progress.

Defense perimeter (pawn fortress)

A ''defense perimeter'' is a drawing technique in which the side behind in or otherwise at a disadvantage sets up a perimeter, largely or wholly composed of a pawn chain, that the opponent cannot penetrate. Unlike other forms of fortress, a defense perimeter can often be set up in the middlegame with many pieces remaining on the board. The position in the first diagram, a

chess problem A chess problem, also called a chess composition, is a puzzle set by the composer using chess pieces on a chess board, which presents the solver with a particular task. For instance, a position may be given with the instruction that White is to ...

by W.E. Rudolph (''La Strategie'' 1912), illustrates the defense perimeter. White already has a huge material disadvantage, but forces a draw by giving up his remaining pieces to establish an impenetrable defense perimeter with his pawns. White draws with 1. Ba4+! Kxa4 (1... Kc4 2. Bb3+! Kb5 3. c4+ Kc6 4. Ba4+!, forcing Rb5, wins for White) 2. b3+ Kb5 3. c4+ Kc6 4. d5+ Kd7 5. e6+! Kxd8 6. f5! (second diagram). Now Black is up two rooks and a bishop (normally an overwhelming material advantage) but has no hope of breaking through White's defense perimeter. The only winning attempts Black can make are to place his rooks on b5, c6, etc. and hope that White them. White draws by ignoring all such offers and simply shuffling his king about. The above example may seem fanciful, but Black achieved a similar defense perimeter in

Arshak Petrosian Arshak B. Petrosian ( hy, Արշակ Պետրոսյան; born December 16, 1953) is an Armenian chess player and National Coach. FIDE awarded him the International Grandmaster title in 1984. He won the Armenian Chess Championship in 1974 and 1976 ...

–Hazai,

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1970 (first diagram) via a swindle. Black has a difficult endgame, since White can attack and win his a-pawn by force, and he has no counterplay. Black tried the extraordinary 45... Qb6!?, to which White replied with the obvious 46. Nxb6+? This is actually a critical mistake, enabling Black to establish an impenetrable fortress. White should have carried out his plan of winning Black's a-pawn, for example with 46.Qc1 (threatening 47.Nxb6+ cxb6 48.h4! gxh4 49.Qh1 and Qh3, winning) Qa7 47.Qd2 followed by Kb3, Nc3, Ka4, and Na2–c1–b3. 46... cxb6 Now Black threatens 47...h4, locking down the entire board with his pawns, so White tries to break the position open. 47. h4 gxh4 48. Qd2 h3! 49. gxh3 Otherwise 49...h2 draws. 49... h4! (second diagram) Black has established his fortress, and now can draw by simply moving his king around. The only way White could attempt to breach the fortress would be a queen sacrifice at some point (for example Qxa5 or Qxe5), but none of these give White winning chances as long as Black keeps his king near the center. The players shuffled their kings, and White's queen, around for six more moves before agreeing to a draw. In Smirin- HIARCS, Smirin-Computers match 2002, the super-grandmaster looked to be in trouble against the computer, which has the , can tie White's king down with ...g3, and threatens to invade with its king on the light squares. Smirin, however, saw that he could set up a fortress with his pawns. The game continued 46... g3 47. h3! A surprising move, giving Black a formidable protected passed pawn on the sixth rank, but it begins to build White's fortress, keeping Black's king out of g4. 47... Bc5 48. Bb4! Now Smirin gives HIARCS the choice between an

opposite-colored bishops endgame The opposite-colored bishops endgame is a chess endgame in which each side has a single bishop and the bishops reside on opposite-colored squares. Without other besides pawns, these endings are widely known for their tendency to result in a dra ...

(in which, moreover, White will play Be7 and win the h-pawn if Black's king comes to the center) and a bishop versus knight ending in which Smirin envisions a fortress. 48... Bxb4 49. axb4 Kf7 Black could try to prevent White's coming maneuver with 49...Bd3, but then White could play 50.Nf3 Kh5 (forced) 51.Nd4. 50. Nb5! Ke6 51. Nc3! Completing the fortress. Now Black's king has no way in, and his bishop can do nothing, since White's king can prevent ...Bf1, attacking White's only pawn on a light square. The game concluded: 51... Bc2 52. Kg2 Kd6 53. Kg1 Kc6 54. Kg2 b5 55. Kg1 Bd3 56. Kg2 Be4+ 57. Kg1 Bc2 58. Kg2 Bd3 59. Kg1 Be4 60. Kf1 ½–½

Other examples

Here are some other drawing fortresses.

Fortresses against a bishop

Fortresses against a knight

Fortresses against a rook

Semi-fortress in two bishops vs. knight

The endgame of two bishops versus a knight was thought to be a draw for more than one hundred years. It was known that the temporary defensive fortress in this position could be broken down after a number of moves, but it was assumed that the fortress could be reformed in another corner. Computer

s show that the bishops generally win, but it takes up to 66 moves. It takes several moves to force Black out of the temporary fortress in the corner; then precise play with the bishops prevents Black from forming the fortress in another corner. The position in the diagram was thought to be a draw by Kling and

Horwitz Horwitz is a surname, current among Ashkenazi Jews. It is derived from the Yiddish pronunciation of the name of the town of Hořovice in Bohemia. For detailed historical background see the Horowitz page . Notable people with the surname include: ...

but computer analysis shows that White wins in 45 moves (either by checkmate or by winning the knight). All of the long wins in this endgame go through this type of semi-fortress position. This game between József Pintér and

David Bronstein David Ionovich Bronstein (russian: Дави́д Ио́нович Бронште́йн; February 19, 1924 – December 5, 2006) was a Soviet and Ukrainian chess player. Awarded the title of International Grandmaster by FIDE in 1950, he narro ...

demonstrates the human play of the endgame. The defender has two ideas: (1) keep the king off the edge of the board and (2) keep the knight close to the king. White reaches the semi-fortress after 71. Nb2!, which falls after 75... Kb5!. White gets to a semi-fortress again in another corner after 90. Ng2+. After 100. Ke3 White cannot hold that semi-fortress any longer, but forms one in another corner after 112. Nb7!. On move 117 White claimed a

draw Draw, drawing, draws, or drawn may refer to: Common uses * Draw (terrain), a terrain feature formed by two parallel ridges or spurs with low ground in between them * Drawing (manufacturing), a process where metal, glass, or plastic or anything ...

by the fifty move rule.

Positional draw

A "positional draw" is a concept most commonly used in

endgame studies In the game of chess, an endgame study, or just study, is a composed position—that is, one that has been made up rather than played in an actual game—presented as a sort of puzzle, in which the aim of the solver is to find the essentially uniqu ...

and describes an impasse other than stalemate. It usually involves the repetition of moves in which neither side can make progress or safely deviate. Typically a advantage is balanced by a positional advantage. Fortresses and

perpetual check In the game of chess, perpetual check is a situation in which one player can a draw by an unending series of checks. This typically arises when the player who is checking cannot deliver checkmate, and failing to continue the series of checks give ...

are examples of positional draws. Sometimes they salvage a draw from a position that seems hopeless because of a material deficit. Grandmaster

John Nunn John Denis Martin Nunn (born 25 April 1955) is an English chess grandmaster, a three-time world champion in chess problem solving, a chess writer and publisher, and a mathematician. He is one of England's strongest chess players and was forme ...

describes a positional draw as a position in which one side has enough material to normally win and he is not under direct attack, but some special feature of the position (often a

blockade A blockade is the act of actively preventing a country or region from receiving or sending out food, supplies, weapons, or communications, and sometimes people, by military force. A blockade differs from an embargo or sanction, which are leg ...

) prevents him from winning. A simple example is shown in the game between Lajos Portisch and

Lubomir Kavalek Lubomir (Lubosh) Kavalek ( cz, Lubomír Kaválek, August 9, 1943 – January 18, 2021) was a Czech-American chess player. He was awarded both the International Master and International Grandmaster titles by FIDE in 1965.Hooper & Whyld 1992, p. 19 ...

. White could have won easily with 1.Be1 Kc6 2.b4. However, play continued 1. b4? Nb8 2. b5 Nc6+! The only way to avoid the threatened 3...Nxa5 is 3.bxc6 Kxc6, but the resultant position is a draw because the bishop is on the wrong color to be able to force the

(see above,

, and

Luděk Pachman Luděk Pachman (German: Ludek Pachmann, May 11, 1924 – March 6, 2003) was a Czechoslovak-German chess grandmaster, chess writer, and political activist. In 1972, after being imprisoned and tortured almost to death by the Communist regime in ...

cites the endgame position in the diagram as a simple example of a positional draw. White on move simply plays waiting moves with the bishop (Bb1–c2–d3). As for Black, "If he is unwilling to allow the transition to the drawn ending of Rook versus Bishop, nothing else remains for him but to move his Rook at 5continuously up and down the -file" Pachman explains, "The indecisive result here contradicts the principles concerning the value of the pieces and is caused by the bad position of the black pieces (pinned rook at 4.". This position from a game between Mikhail Botvinnik and

Paul Keres Paul Keres (; 7 January 1916 – 5 June 1975) was an Estonian chess grandmaster and chess writer. He was among the world's top players from the mid-1930s to the mid-1960s, and narrowly missed a chance at a World Chess Championship match on five ...

in the 1951 USSR Championship is drawn because the black king cannot get free and the rook must stay on the c-. The players agreed to a draw four moves later. The first diagram shows a position from a game between former

World Champion A world championship is generally an international competition open to elite competitors from around the world, representing their nations, and winning such an event will be considered the highest or near highest achievement in the sport, game, ...

Mikhail Tal Mikhail Nekhemyevich Tal; rus, Михаил Нехемьевич Таль, ''Mikhail Nekhem'yevich Tal' '', ; sometimes transliterated ''Mihails Tals'' or ''Mihail Tal'' (9 November 1936 – 28 June 1992) was a Soviet-Latvian chess player ...

and future World Champion

Bobby Fischer Robert James Fischer (March 9, 1943January 17, 2008) was an American chess grandmaster and the eleventh World Chess Champion. A chess prodigy, he won his first of a record eight US Championships at the age of 14. In 1964, he won with an 1 ...

from the 1962 Candidates Tournament in Curaçao. After 41 moves Tal had the advantage but Fischer sacrificed the exchange (a rook for a knight). The game was drawn on the 58th move. In this position from a game between

Pal Benko Pál C. Benkő ( hu, Benkő Pál; July 15, 1928 – August 26, 2019) was a Hungarian-American chess player, author, and composer of endgame studies and chess problems. Early life Benko was born on July 15, 1928 in Amiens, France, where his ...

and International Master Jay Bonin, White realized that the blockade cannot be broken and the game is a draw despite the extra material. The position looks lost for White, as he cannot stop the h-pawn from queening, but he does have a defence which seems to defy the rules of logic. White will calmly construct a "fortress" which will hide his pieces from attack. The only weakness in White's "fortress" is the g-pawn. This pawn has to be defended by the bishop and the only square where this can be done safely is from h6. 1. Bf6! White threatens to stop the advance of the h-pawn with ...Be5+; building the fortress immediately does not work: 1.f6? h2 2.Kf8 h1=Q 3.Kg7 (3.Kg8 Qg2 4.Bf8 Qa8 5.Kg7 Kd7 6.Kg8 Ke6 7.Kg7 Kf5 8.Kg8 Bb3 9.Kg7 Qh1−+) 3...Kd7 4.Bb4 Ke6 5.Bd2 Kf5 6.Be3 Qf3 7.Bd2 Qe2 8.Bc1 Qd1 9.Be3 Qd3 10.Bc1 Qc3−+; 1... Kd6 2. Be7+ 2.fxg6? This move destroys the fortress 2...fxg6 3.Be7+ Kc6−+. 2...Kc6 2... Ke5 White draws without a fortress after 3.fxg6 fxg6 4.Bd8 Kd6 5.Nf6! h2 6.Ne4+ Ke6 7.Nf2 Bd5 8.Bf6 h1=Q 9.Nxh1 Bxh1=; 3. f6! Chess computer programs have difficulty assessing "fortress" positions because the normal values for the pieces do not apply. White has achieved the closing of the long diagonal a8–h1. The only way to avoid this would be for Black to repeat moves. Now White can build his "fortress" without the worry of the queen getting to the back rank via the long diagonal. 3...h2 4. Bf8! h1=Q 5. Bh6! with the idea of 6.Kf8 and 7.Kg7. White will be safe behind the barrier of pawns. It is a positional draw.

References

Bibliography * * * * * * * * * * * * * * (chapter 11 gives extensive coverage to fortresses) * * * * * * * * * * {{DEFAULTSORT:Fortress (Chess) Chess terminology Chess strategy Chess endgames Chess theory Chess tactics