Chess tactics

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In chess, a tactics refers to a short sequence of moves which limits the opponent's options and which results in tangible gain. Tactics are usually contrasted to strategy, in which advantages take longer to be realized, and the opponent is less constrained in responding.

The fundamental building blocks of tactics are two-move sequences in which the first move poses a double threat. The opponent is unable to respond to both threats in one move, so the first player realizes an advantage on the second move. This class of tactic includes forks, skewers, discovered attacks, undermining, overloading, and interference. Pins also fall into this category to some extent, although it is common for a defending player to relieve neither of the two threats posed by a pin, in which case the attacking player commonly maintains the pin for a longer period of time. A pin is therefore sometimes more strategic than tactical.

Often tactics of several types are conjoined in a combination. A combination, while still constraining the opponent's responses, takes several moves to obtain advantage, and thus is considered deeper and more spectacular than the basic tactics listed above.

The concept of zwischenzug is often listed as a tactic, but might properly be called a counter-tactic instead. During the execution of a tactic one focuses on only a few pieces as relevant, but a zwischenzug complicates the situation by making a more urgent threat with another piece. The effect of a zwischenzug is to change the status quo before a tactic can come to fruition. The near ubiquity of the zwischenzug makes long combinations all the more rare and impressive.

Chess computers are considered superhuman at tactics and rather weak at strategy. The fact that computers can play on a par with the best humans suggests that chess is primarily a tactical game. On the other hand, it must be noted that computers don't think about tactics in human terms (fork, skewer, etc.); the nuances of human understanding of chess, both tactical and strategic, have not been imitated by computers, only matched in effective playing strength.

1 Attacking and defending pieces
2 Forks
3 Pins
4 Skewers
5 Discovered attacks
6 Zwischenzug
- 6.1 Sacrifices
7 Zugzwang
8 Attacks against the king
9 See also
10 Further reading
11 External links

[edit] Attacking and defending pieces

A piece is said to attack an opponent's piece if, in the next move, it could capture that piece. A piece is said to defend or to protect a piece of the defender's color if, in case the defended piece were taken by the opponent, the defender could recapture right away. Attacking a piece forces the opponent to respond only if the attacked piece is undefended, or if the attacking piece is of lower value than the attacked one.

[edit] Forks

Main article: fork

A fork is a move that uses one piece to attack two of the opponent's pieces at the same time, hoping to achieve material advantage (because the opponent can only counter one of the two threats). Knights are often used for forks: they jump to a position from where they attack two pieces. A quite common situation is a white knight jumping to c7, thereby threatening both the rook at a8 and the king at e8. Such "king forks" are particularly effective, because the opponent is forced by the rules of the game to counter the threat to the king; the opponent cannot choose to defend the other piece, and thus cannot use a zwischenzug (see below) to complicate the situation. Pawns can also fork enemy pieces: by moving a pawn forward, it may attack two pieces: one diagonally to the left and one diagonally to the right. A common situation is the move Pawn d2-d4 forking a black bishop at c5 and a black knight at e5.


Kasparov vs. World Team 1999 Kasparov played 12.Nc7+	A variation of the Three Knights Opening 1.e4 e5 2.Nf3 Nc6 3.Nc3 Bc5 4.Nxe5 Nxe5 5.d4

A queen move also often attacks two pieces at the same time, but this is only useful if both pieces are undefended, or if one is undefended and the other is the opposing king. The queen is more valuable than the pieces it is attacking, so it is usually not profitable for it to capture a defended piece.

[edit] Pins

Main article: pin

"The defensive power of a pinned piece is only imaginary." - Aron Nimzowitsch

A pin is a move which forces one of the opponent's pieces to stay put because moving it would expose a more valuable piece behind it. As they move in a straight line, bishops, rooks, and queens can pin other pieces.

In the left diagram, black can't move the knight without losing the queen, and Black's rook can't be moved at all. In the right diagram, Kramnik pins black's bishop and soon wins it with a4-a5.


Morphy vs. Consultation Team 1858 after Morphy's 14th move	Vladimir Kramnik vs. Alexander Morozevich 2002 Rapid Play Kramnik played 31.Rb1

[edit] Skewers

Main article: skewer

A skewer is a move which attacks two pieces in a line, similar to a pin, except that the enemy piece of greater value is in front of the enemy piece of lesser value. After the more valuable piece moves away, the lesser piece can be captured. Queens, rooks, and bishops can skewer.


Lasker vs. Bauer 1889 Lasker played 33.Qg7+	Tal vs. Botvinnik 1960 Tal played 30.Bc4

Because of possible pins and skewers, one should be extremely cautious if king and queen are located on the same vertical, horizontal or diagonal line, or can be forced into such an arrangement.

[edit] Discovered attacks

Main article: discovered attack

A discovered attack is a move which unmasks an attack by another piece. A piece is moved away so as to unmask the attack of a friendly bishop, rook or queen on an enemy piece. If the attacked piece is the king, we speak of a discovered check. Discovered attacks are powerful, because if the moving piece manages to pose a second threat, the opponent is in trouble.


Torre vs. Lasker 1925 Torre played 31.Rg5+	Byrne vs. Fischer 1956 Fischer played 22...Nc3+

A special case of a discovered check is a double check, where both the piece being unmasked and the piece being moved attack the enemy king. A double check requires that the opponent moves his/her king as the king is under attack from two directions and it is impossible to counter both at the same time in any other way.

[edit] Zwischenzug

Main article: zwischenzug

The German zwischenzug means "intermediate move"; it is a common tactic that occurs in almost every game: instead of countering a direct threat, which the opponent expects, a move is played which poses an even more devastating threat, often an attack against the queen or the king. The opponent has to counter that threat first, and this will ideally change the situation to a disadvantage.

When a player plans the tactics, he or she should always watch out for a zwischenzug. Don't assume that the opponent has to counter all threats immediately. It is good practice to always check whether the opponent has a check or a move threatening the player's queen. Conversely, it is good to anticipate the opponent's threats and plan a surprising zwischenzug.

[edit] Sacrifices

Main articles: gambit, exchange sacrifice

Often it is necessary to throw the opponent's position or tempo out of balance by first sacrificing some material, sometimes to be regained with interest a couple of moves later. Pawn sacrifices in the opening are known as gambits; they are usually not intended for material short-term gain but instead to achieve a more active position.

Direct attacks against the enemy king are often started by sacrifices; a common example is a bishop sacrificing itself on h7, checking the king on g8 who has to take the bishop, after which the white queen and knight develop a fulminant attack.

[edit] Zugzwang

Main article: zugzwang

In chess, zugzwang (German for "compulsion to move") occurs when one player, because it is his turn to move, must make a move but every possible move weakens his position. The player is put at a disadvantage because he would like to pass and make no move, but a move has to be made. Situations involving zugzwang occur uncommonly; when they do occur, it is most commonly in the endgame, where there are fewer choices of available moves.

[edit] Attacks against the king

Colle vs. O'Hanlon, 1930
Colle played 12.Bxh7+

Attacks against the castled king are usually justified by some imbalance: the attacker has more firepower on the king's side than the opponent, or the opponent weakened his king's position by moving one of the pawns in front of the king.

Many mating attacks are introduced by sacrifices: if mate is the goal, material doesn't matter anymore. The queen is almost always the most important piece in a mating attack, since she has various ways of mating a king. The most common is a direct "contact check" while being protected by one of her own pieces. For instance, white knight g5, black king on g8 and the queen mates at h7, or white bishop at f6 or h6 and the white queen on g7 mates the black king on g8.

One should not assume that every move in a mating attack has to be a check. Often, a check just drives the king to a better position, or weakens the attacker's setup. It is good to look for "quiet" moves which seal the deal.