Pins and skewers: two tactics along one line
A pin freezes a piece in front of a more valuable one; a skewer attacks the valuable piece first and takes what stands behind it. Both work along a straight line, and both become much easier to see once you know their signals.
What a pin is
A pin is an attack on a piece that cannot move without exposing a more valuable piece behind it. Only the pieces that move along lines can pin: the bishop on diagonals, the rook on ranks and files, the queen on both. The pinned piece is still on the board, but it is frozen, and a frozen piece is a target.
In the Lichess puzzle database (6.2 million puzzles), the pin comes up in 6.0% of the puzzles, almost three times as often as the skewer (2.2%). Pins and skewers are two of the ten themes of 300 Chess Puzzles, with thirty puzzles each, from about 600 to 1800 Elo. Here is how to use them, and how to get out of them.
Three signals of a pin
- An enemy piece in front of its own king or queen, on a line your bishop, rook or queen can reach. That is a pin waiting to be played.
- A piece pinned to its king cannot leave the line. Attack it again, with a pawn if you can: it cannot step aside.
- A pinned piece does not really defend. What it seems to protect may be free to take.
1…Ra3 puts the rook on that rank, and the bishop is pinned to its king. A bishop never moves along a rank, so it cannot move at all, and nothing defends it. After 2.Ke3, 2…Rxc3+ takes it. Stepping off the rank with the king does not help: the bishop is still attacked, and Black takes it all the same.
Absolute and relative pins
The pin on c3 was absolute: the piece behind the bishop was the king, and no move may leave your own king in check. When the piece behind is any other piece, a queen or a rook for example, the pin is relative: the pinned piece may move, but it gives up what stands behind it.
An absolute pin can win a queen in the opening. In the London System, after 1.d4 d5 2.Bf4 Bf5 3.e3 e6 4.Nf3 Nf6 5.Bd3 Bg6 6.c3 c5 7.Bxb8 Rxb8 8.Qa4+, Black blocks the check with the queen, 8…Qd7?, and 9.Bb5! pins it to the king: Black has to give it up for the bishop. The example comes from lesson 3 of The London System in Twelve Lessons.
A relative pin is different: it can be broken, and sometimes breaking it wins the game. A classic trap of the Scotch, Légal’s mate, begins with 1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.c3 dxc3 5.Nxc3 d6 6.Bc4 Bg4 7.O-O Ne5?: the black knight attacks the bishop on c4, and White’s knight on f3 seems unable to move.
8.Nxe5! moves the knight anyway and gives up the queen. If Black takes it, 8…Bxd1 9.Bxf7+ Ke7 10.Nd5#: three minor pieces mate the king. If Black does not, 8…dxe5 9.Qxg4 wins White a piece for a pawn. Légal’s mate is one of the ten traps in The Scotch Game in Twelve Lessons, and our article on Scotch Game traps shows it with two others.
The skewer: a pin in reverse
A skewer works along the same kind of line, from the other end: the valuable piece stands in front. You attack it, it has to move, and you take what was behind it. Its signals:
- A king or a queen on a rank, a file or a diagonal, with another piece behind it.
- A check along that line. The king must step aside and give up what stands behind it.
- In the endgame, a king and a rook on the same line are a classic target.
1.Qg7+ checks the king along the long diagonal. Wherever the king goes, for example 1…Kd5, it leaves the line, and 2.Qxa1 takes the queen. The checks right next to the king fail: after 1.Qf4+?, for example, nothing protects the queen, and 1…Kxf4 takes it.
A skewer does not even need a check. In one of the worked examples of 300 Chess Puzzles, a white bishop goes to d2 and attacks the black queen on c3, with a black bishop behind it on b4. The queen has to move, and the bishop falls: 1.Bd2 Qc7 2.Bxb4.
How to escape a pin or a skewer
The best defence is not to stand on the line in the first place. Before each move, look at the lines that lead to your king and your queen: an open file, a long diagonal, a rank in the endgame. Two of your pieces on one of them, with an enemy bishop, rook or queen able to reach it: that is an invitation. When it is too late for that:
- Block with a cheaper piece. In the London example, 8…Nd7 instead of 8…Qd7? blocks the check with the knight. The knight is pinned in turn, but the queen and the king defend it, and Stockfish rates the position as equal.
- Protect what stands behind. A skewer only pays when the piece at the back can be taken for free, or is worth more than the piece that takes it.
- Attack the pinning piece, or add a defender to the pinned one: a pinned piece that is well defended is only a nuisance.
- Break a relative pin when it pays, as White did in Légal’s mate. Count first: what you win must be worth more than what you leave behind.
How to train your eye
Pins and skewers become easier to see with repetition. When you solve a puzzle, name the line first: which two pieces stand on it, and which of your pieces can reach it. Then write all the moves on paper before you check the answer, as you would have to calculate them in a game. Our article on how to calculate in chess gives a method for that.
The twenty free puzzles of our Lichess study include two pins and two skewers. The fork, which also hits two pieces at once, has its own article, and our guide to the ten tactical patterns shows how they all fit together.