Basic Chess Tactics: Fork, Pin and Skewer

If you read chess books or watch chess videos, the words fork, pin and skewer come up all the time. Each is the name of a fixed pattern that wins material in one move or two. Short sequences like these are called tactics.

For many beginners the names are familiar but the shapes are not. In this post I go through the three patterns one at a time, each in a small position. Each position was checked with a program: the moves are legal and Black loses material whatever it plays.

1. Fork: one piece attacks two

A fork is one piece attacking two enemy pieces at once. The opponent cannot save both in one move, so you win one of them. The name comes from the two prongs of a table fork.

Position 1: White king on g1, knight on b5, pawns on f2, g2 and h2. Black king on e8, rook on a8, pawns on a7, f7, g7 and h7. White to move.

White plays Nc7+. The knight on c7 checks the king on e8 and at the same time attacks the rook on a8. Black has to answer the check, and the only way is to move the king. No black piece covers c7, so the knight cannot be taken. Wherever the black king goes, White plays Nxa8 next and wins the rook.

A fork you will see very often is a knight fork like this one. The knight’s odd way of moving plays a part: its reach rarely overlaps with other pieces, so the opponent can miss it. There are also pawn forks, where a pawn attacks two pieces diagonally in front of it, and queen forks along a file and a diagonal.

One way to spot forks is to look first for the enemy king and for big pieces, rooks and queens, that are not protected. If there is a square that touches two of them, ask whether one of your pieces can get there. A fork that comes with check is especially strong, because it leaves the opponent no choice.

2. Pin: a piece that cannot move because of what is behind it

A pin lines up an enemy piece with a more valuable piece behind it, so the front piece cannot move. Think of a piece pinned to the board. Only long-range pieces can pin: bishops, rooks and queens.

Position 2: White king on g1, bishop on b5, pawns on d4, f2, g2 and h2. Black king on e8, knight on c6, pawns on a7, f7, g7 and h7. White to move.

From b5 the diagonal runs through c6 and d7 to e8. If the black knight on c6 moved, the king behind it would be in check from the bishop, so by the rules the knight cannot move at all. When the piece behind is the king and moving is simply illegal, it is called an absolute pin.

Now White plays d5. The pawn attacks the knight, which cannot run. Whatever Black plays, White takes the knight next move with the pawn or the bishop. If Black moves the king to e7, the pin is broken, but White’s turn comes before the knight can get away.

A pin by itself does not win anything. As in this example, you gain material when you attack the pinned piece again. When the piece behind is a queen or a rook rather than the king, the front piece is allowed to move, but if it does, the piece behind is lost. That is called a relative pin.

3. Skewer: move the front piece, take the one behind

A skewer is also a straight line, but the order is reversed. The valuable piece is in front, and another piece is behind it. When the front piece moves away, the one behind is taken. The image is meat on a skewer, two pieces run through on one line.

Position 3: White king on g1, rook on a1, pawns on f2, g2 and h2. Black king on e5, queen on e8, pawns on a7, f7, g7 and h7. White to move.

White plays Re1+. The rook, the black king and the black queen are now on one line, the e-file. Black has to step off the file to get out of check, and the queen cannot come between. Wherever the king goes, White plays Rxe8 and takes the queen with a rook.

The difference between a pin and a skewer is which piece is in front. A smaller piece in front of a bigger one is a pin. A bigger piece in front, very often the king, with another piece behind is a skewer. Both depend on noticing that two enemy pieces stand on one line.

The same idea in shogi

If you play shogi, a fork is what shogi players call ryōdori, a double attack. The knight fork in shogi and the check that also attacks the rook, called ōte-bisha, work almost exactly like a chess knight fork. The skewer has a shogi counterpart too: running a lance, rook or bishop through two pieces on one line is called dengaku-zashi, after a skewered dish.

There is one big difference. In shogi, captured pieces can be dropped back on the board, so winning a piece feeds straight into the next attack. In chess, captured pieces leave the game, so the material difference stays until the ending. How much each piece is worth is in Chess piece values.

If you learn one first, learn the fork

A natural one to start with is the knight fork. It comes up often in games between beginners, and you will be on both sides of it. Before you move, just checking “after this, is there a square where the enemy knight gives check and hits two things?” will save games.

Pins and skewers both train you to see straight lines, so it is easiest to learn them together. When your king and queen end up on the same file, rank or diagonal, check whether an enemy bishop or rook can get onto that line.

Mate puzzles and tactics puzzles

Chess puzzle collections usually have two kinds of problems: mate puzzles and puzzles about winning material. They look separate, but they are connected. Many forks, pins and skewers work because the opponent is forced to look after the king. Solving mate puzzles builds the sense that a player in check has only a few options.

On the other hand, mate puzzles alone do not train you to win material and then convert it. If you want to practise tactics in general, you can use a place where you can choose problems by theme. The free chess site Lichess, for example, has a puzzle page where you can pick themes such as fork, pin and skewer. English Wikipedia has more detail on each pattern in Fork, Pin and Skewer.

Daily mate practice

Chess365 is a checkmate puzzle app with 1,000 puzzles each of mate in 2, 3, 4 and 5. It focuses on mates, not general tactics. You always play White, you can make any legal move, and Black answers with the most stubborn defence. Many solutions are quiet moves that are not checks, which trains you to look at how many escape squares the enemy king still has. All puzzles are free, and a one-time purchase removes the ads.

Basic mates are in How to Checkmate with King and Rook and Back rank mate, and how to use the app is in Getting Started with Chess365.