checkmate

This article uses algebraic notation to describe chess moves.

The black king has been checkmated; the game is over.

Checkmate (frequently shortened to mate) is a situation in chess (and in other boardgames of the chaturanga family) in which one player's king is threatened with capture (in check) and there is no way to meet that threat. Or, simply put, the king is under direct attack and cannot avoid being captured. Delivering checkmate is the ultimate goal in chess: a player who is checkmated loses the game (the king is never actually captured – the game ends as soon as the king is checkmated because checkmate leaves the defensive player with no legal moves). In practice, most players resign an inevitably lost game before being checkmated.

If a king is under attack but the threat can be met, then the king is said to be in check, but is not in checkmate. If a player is not in check but has no legal move (that is, every possible move would put the king in check), the result of the game is stalemate, and the game ends in a draw (but in other variants, it is a loss for the stalemated player). (See rules of chess.)

A checkmating move is denoted in algebraic chess notation with the hash symbol (#) – for example, 34.Qh8# or by "++". (The symbol "++" is sometimes used to indicate double check.)

Origin of the word

The term checkmate is an alteration or Hobson-Jobson of the Persian phrase "Shāh Māt" which means, literally, "the King is ambushed" (or "helpless" or "defeated"). It does not literally mean "the King is dead", although that is a common misconception, as chess reached Europe via the Islamic world, and Arabic māta مَاتَ means "died", "is dead".^[1]

Moghadam traced the etymology of the word mate. It comes from a Persian verb mandan, meaning "to remain", which is cognate with the Latin word manco. It means "remained" in the sense of "abandoned" and the formal translation is "surprised", in the military sense of "ambushed" (not in the sense of "astonished"). So the king is in mate when he is ambushed, at a loss, or abandoned to his fate (Davidson 1981:70-71).

The term checkmate has come to mean in modern parlance an irrefutable and strategic victory.

Examples

Fool's mate

White is in checkmate

Byrne-Fischer, 1956

After 41... Rc2, checkmate

Checkmate with a rook

Black has been checkmated

A checkmate may occur in as few as two moves with all of the pieces still on the board (as in Fool's mate, in the opening phase of the game), in a middlegame position (as in the Game of the Century between Donald Byrne and Bobby Fischer),^[2] or after many moves with as few as three pieces in an endgame position.

Two major pieces

White checkmates easily

Checkmate with queen and rook

Two major pieces (queens or rooks) can easily force checkmate on the edge of the board, even without the help of their king. The process is to put the two pieces on adjacent ranks or files and gradually force the king to the side of the board, where one piece keeps the king on the edge of the board while the other delivers checkmate (Pandolfini 1988:18-20).

In the first diagram, White checkmates easily by forcing the black king to the edge a rank at a time or a file at a time:

1. Qg5+ Kd4

2. Rf4+ Ke3

3. Qg3+ Ke2

4. Rf2+ Ke1

5. Qg1# (second diagram) (Silman 2007:7-8).

The checkmate with two queens or with two rooks is similar (Pandolfini 1988:20).

Mid-board checkmate with king and two rooks

Mid-board checkmate with two queens

Another mid-board checkmate with two queens

Checkmate can be forced even away from the edge of the board with two rooks and a king, or with a queen, rook, and king, while two queens are able to force checkmate in the center without the help of the king (Pandolfini 2009:32-33).

Basic checkmates

Here are the common fundamental checkmates when one side has only his king and the other side has only the minimum material needed to force checkmate, i.e. (1) one queen, (2) one rook, (3) two bishops on opposite-colored squares, or (4) a bishop and a knight. The king must help in accomplishing all of these checkmates. If the superior side has more material, checkmates are easier (Silman 2007:33).

The checkmate with the queen is the most important, but it is also very easy to achieve. It often occurs after a pawn has queened. The next most important one is the checkmate with the rook, and it is also very easy to achieve. The checkmates with the two bishops and with a bishop and knight are not nearly as important, since they only occur infrequently. The two bishop checkmate is fairly easy to accomplish, but the bishop and knight checkmate is difficult and requires precision.

King and queen

Checkmate with the queen

A second checkmate with the queen

A third type of checkmate

A fourth type of checkmate

The first two diagrams show representatives of the basic checkmate positions with a queen, which can occur on any edge of the board. Naturally, the exact position can vary from the diagram. In the first of the checkmate positions, the queen is directly in front of the opposing king and the white king is protecting its queen. In the second checkmate position, the kings are in opposition and the queen mates on the rank (or file) of the king. See Wikibooks - Chess/The Endgame for a demonstration of how the king and queen versus king mate is achieved.

White checkmates easily

With the side with the queen to move, checkmate can be forced in at most ten moves from any starting position, with optimal play by both sides, but usually fewer moves are required (Fine & Benko 2003:1-2). (Müller & Lamprecht 2001:16). In positions in which a pawn has just promoted to a queen, at most nine moves are required (Levy & Newborn 1991:144). In this position, White checkmates by confining the black king to a rectangle and shrinking the rectangle to force the king to the edge of the board:

1. Qf6 Kd5

2. Qe7 Kd4

3. Kc2 Kd5

4. Kc3 Kc6

5. Kc4 Kb6

6. Qd7 Ka6

7. Qb5+ Ka7

8. Kc5 Ka8

9. Kc6 Ka7

10. Qb7# (Seirawan 2003:4-5).

Stalemate if Black is to move. The white king can be anywhere (except a7, b7, or b8).

Stalemate if Black is to move

The superior side must be careful to not stalemate the opposing king, whereas the defender would like to get into such a position. There are two general types of stalemate positions that can occur, which the winning side must avoid (Fine & Benko 2003:2).

King and rook

Checkmate with the rook

A second checkmate with the rook

The first diagram shows the basic checkmate position with a rook, which can occur on any edge of the board. The black king can be on any square on the edge of the board, the white king is in opposition to it, and the rook can check from any square on the rank or file (assuming that it can not be captured). The second diagram shows a slightly different position where the kings are not in opposition but the defending king must be in a corner.

With the side with the rook to move, checkmate can be forced in at most sixteen moves from any starting position (Fine & Benko 2003:2). Again, see Wikibooks - Chess/The Endgame for a demonstration of how the king and rook versus king mate is achieved.

White checkmates by boxing in the black king.

In this position, White checkmates by confining the black king to a rectangle and shrinking the rectangle to force the king to the edge of the board:

1. Kd3+ Kd5

2. Re4 Kd6

3. Kc4! Kc6

4. Re6+ Kc7

5. Kc5 Kd7

6. Kd5 Kc7

7. Rd6 Kb7

8. Rc6 Ka7

9. Kc5 Kb7

10. Kb5 Ka7

11. Rb6 Ka8

12. Kc6 Ka7

13. Kc7 Ka8

14. Ra6# (second checkmate position) (Seirawan 2003:1-4)

There are two stalemate positions to watch out for: (Fine & Benko 2003:2-3):

Stalemate if Black is to move

Stalemate if Black is to move

King and two bishops

Checkmate with two bishops

Here are the two basic checkmate positions with two bishops (on opposite-colored squares), which can occur in any corner. (Two bishops or more on the same color cannot checkmate.) The first is a checkmate in the corner. The second one is a checkmate in a side square next to the corner square. With the side with the bishops to move, checkmate can be forced in at most nineteen moves (Müller & Lamprecht 2001:17).

A second checkmate with two bishops

It is not too difficult for two bishops to force checkmate, with the aid of their king. Two principles apply:

• The bishops are best when they are near the center of the board and on adjacent diagonals. This cuts off the opposing king.
• The king must be used aggressively, in conjunction with the bishops.

Two bishops (and king) can force checkmate. From Seirawan.

In the position from Seirawan, White wins by first forcing the black king to the side of the board, then to a corner, and then checkmates. It can be any side of the board and any corner. The process is:

1. Ke2 Ke4 (Black tries to keep his king near the center)

2. Be3 Ke5 (forcing the king back, which is done often)

3. Kd3 Kd5

4. Bd4 Ke6

5. Ke4 Kd6 (Black tries a different approach to stay near the center)

6. Bc4 (White has a fine position. The bishops are centralized and the king is active.)

6... Kc6 (Black avoids going toward the side)

7. Ke5 Kd7 (Black is trying to avoid the a8 corner)

8. Bd5 (keeping the black king off c6)

8... Kc7

9. Bc5 Kd7

10. Bd6! (an important move that forces the king to the edge of the board)

10... Ke8 (Black is still avoiding the corner)

11. Ke6 (now the black king cannot get off the edge of the board)

11... Kd8

12. Bc6 (forcing the king toward the corner)

12... Kc8 (Black's king is confined to c8 and d8. The white king must cover a7 and b7)

13. Kd5 (13. Ke7? is stalemate)

13...Kd8

14. Kc5 Kc8

15. Kb6 Kd8 (Now White must allow the king to move into the corner)

16. Bc5 Kc8

17. Be7! (an important move that forces the king toward the corner)

17... Kb8

18. Bd7! (the same principle as the previous move)

18... Ka8

19. Bd8 (White must make a move that gives up a tempo. This move is such a move, along with Bc5, Bf8, Be6, or Ka6.)

19... Kb8

20. Bc7+ Ka8

21. Bc6#, as in the first diagram in this section (Seirawan 2003:5-7).

Note that this is not the shortest forced checkmate from this position. Müller and Lamprecht give a fifteen move solution, however it contains an inaccurate move by Black (according to endgame tablebases) (Müller & Lamprecht 2001:17). With optimal play by both sides, checkmate in this position requires seventeen moves. The longer variation is more instructive.

King, bishop and knight

A checkmate with a bishop and knight

A second checkmate with a bishop and knight

Of the basic checkmates, this is the most difficult one to force, because these two pieces cannot form a linear barrier to the enemy king from a distance. Also, the checkmate can be forced only in a corner that the bishop controls.

Here are the two basic checkmate positions with a bishop and a knight, or the bishop and knight checkmate. The first position is a checkmate by the bishop, with the king in the corner. The second position is a checkmate by the knight, with the king in a side square next to the corner. Alternatively, the knight can be on c6 or d7 in the second position.

With the side with the bishop and knight to move, checkmate can be forced in at most thirty-three moves from any starting position (Müller & Lamprecht 2001:19), except those in which the defending king is initially forking the bishop and knight and it is not possible to defend both. However, the mating process requires accurate play, since a few errors could result in a draw either by the fifty-move rule or stalemate.

Opinions differ as to whether or not or not a player should learn this checkmate procedure. James Howell omits the checkmate with two bishops in his book because it rarely occurs but includes the bishop and knight checkmate. Howell says that he has had it three times (always on the defending side) and that it occurs more often than the checkmate with two bishops (Howell 1997:138). On the other hand, Jeremy Silman includes the checkmate with two bishops but not the bishop plus knight checkmate because he has had it only once and his friend John Watson has never had it (Silman 2007:33,188). Silman says

"...mastering it would take a significant chunk of time. Should the chess hopeful really spend many of his precious hours he's put aside for chess study learning an endgame he will achieve (at most) only once or twice in his lifetime?"

Two knights

Two knights and their king cannot force a checkmate, although there are checkmate positions such as this one.

Two knights cannot force checkmate if Black plays 1... Kc8.

Two knights cannot force checkmate.

It is impossible to force checkmate with a king and two knights, although checkmate positions are possible (see the first diagram). In the second diagram, if Black plays 1... Ka8? White can checkmate with 2. Nbc7#, but Black can play 1... Kc8 and escape the threat. The defender's task is easy — he simply has to avoid moving into a position in which he can be checkmated on the next move, and he always has another move available in such situations (Speelman, Tisdall & Wade 1993:11).

In the third diagram, White can play 1. Nc6+ Ka8, but now if White plays 2. Nb5 threatening 3. Nc7#, Black is stalemated. It is sometimes possible to force checkmate with two knights against a pawn, because in some positions, having a pawn removes this stalemate defence.

Under some circumstances, two knights and a king can force checkmate against a king and pawn (or rarely more pawns). The winning plan, quite difficult to execute in practice, is to blockade the enemy pawn(s) with one of the knights, maneuver the enemy king into a stalemated position, then bring the other knight over to checkmate. (See two knights endgame.)

Three knights

Three knights and a king can force checkmate against a lone king within twenty moves (Fine 1941:5-6). These situations are generally only seen in chess problems, since one or more of the knights must be a promoted piece, and there is very rarely a reason (e.g., avoidance of stalemate) to promote a pawn to anything other than a queen (see underpromotion).

Rare checkmate positions

In some rare positions it is possible to force checkmate with a king and bishop versus a king and pawn or a king and knight versus a king and pawn.

Stamma's mate

White wins by Stamma's mate, with or without the move

In the diagram showing Stamma's mate (named for Philipp Stamma), White to move wins (Emms 2004:122):

1. Nb4+ Ka1

2. Kc1 a2

3. Nc2#

White also wins if Black is to move first:

1. ... Ka1

2. Nc1 a2

3. Nb3#

Nogueiras-Gongora, 2001

White to move wins

This checkmate has occurred in actual games, see the game between Jesus Nogueiras and Maikel Gongora^[3] from the 2001 Cuban Championship, (see diagram) which proceeded

81. Kc2 Ka1

82. Nc5 Ka2 (if 82... a2 then 83. Nb3#)

83. Nd3 (reaching the position in the first diagram above, with Black to move)

83... Ka1

84. Nc1

Black resigned here, but play would continue:

84... a2

85. Nb3# (Snape 2003:55).

Unusual checkmate positions

There are also positions in which a king and a knight can checkmate a king and a bishop, knight, or rook; or a king and a bishop can checkmate a king with a bishop on the other color of squares or with a knight, but the checkmate cannot be forced if there is no other material on the board (see the diagrams for some examples). Nevertheless, it keeps these material combinations from being ruled a draw because of "insufficient mating material" or "impossibility of checkmate" under the FIDE rules of chess.^{[note 1]}

(Pandolfini 2009:63)

Checkmate, but cannot be forced

Pandolfini

Checkmate, but cannot be forced

Pandolfini

Checkmate, but cannot be forced