A skewer is a chess tactic that occurs when an attacked piece must move to safety but will expose a lower-valued piece (or target) behind it. A skewer is sometimes referred to as a “reversed pin”.
Relative skewer vs. Absolute skewer
Since pin tactics and skewer tactics appear to be very similar (both exploit two targets present on the same file, rank or diagonal), this article will mainly focus on the differences between a pin and a skewer.
What is the difference between a pin and a skewer?
The important observation is that in the case of a skewer, the attacked piece has a higher relative value to the piece behind it. This is in contrast to a pin where the lower-valued piece is in the front.
Skewers are often more forcing than pin tactics
The only difference between the diagram above and the one below is that the positions of the black rook and knight is swapped around. It shows that a skewer is often more threatening than a pin.
Even though skewers are similar to pin tactics, they do have certain advantages over pins. First of all, the threat created by a skewer is more direct and (usually) more effective in winning material.
Additionally, since a skewer makes a threat against a higher-valued piece, it is usually harder to escape skewer tactics.
A useful trick in setting up a skewer in chess
In a significant amount cases, skewer tactics become possible as the result of a clever preparation move:
A piece-exchange. Here is a simple example to illustrate the idea:
White uses a piece-exchange to lure a higher-valued piece to a square where it becomes a target. (The idea of using exchanges to create new targets works in many other tactical motifs too).
This example also shows why it is so important to consider all moves where you can capture one of your opponent’s pieces (even if they can capture you back). You have to check whether you can create a new target by means of the exchange.
How to escape from skewer tactics
We aren’t computers – we make mistakes. And being trapped in a skewer tactic will in most cases cause you to lose material. However, don’t accept your fate right away. There are usually a few ideas you can consider to help you find a way out.
“Escape ideas” are almost always based on creating some kind of counter-attack with one of the pieces your opponent is targeting.
Here are a few simple examples that illustrate the main ideas you can use to escape from skewer tactics:
1. Make a threat or check (tempo-move) with one of the pieces trapped in the skewer tactic
The white queen can escape by using a check as a tempo move, Qd5+.
Black has to deal with the check, which gives white time to save the Ra1 on the next move.
2. Use a counter-tactic to remove the piece responsible for the skewer
White can escape by playing Re7+, followed by Rxb7 – removing the bishop responsible for the skewer on white’s queen and rook.
3. Move the skewered piece to protect the target behind it at the same time
Black can move the black queen to safety and at the same time protect the Re8, by playing Qb8.
4. Block the skewering piece by moving a defender in-between
White can play 1.f4 and escape by blocking the attack from the black bishop.
Of course you will not always be able to escape from tactics. You should always try to avoid being trapped in the first place. However, even if you overlooked something, there is often a way out. Don’t give up right away!
Summary: The difference between a pin and a skewer
Even though a pin and a skewer visually appear quite similar, their impact on the position is very different.
So to summarize the difference between a pin and a skewer: A pinned piece shouldn’t move because it would expose a higher-valued target behind it. A skewered piece should move, even though it will expose another target behind it, because the skewered piece has a higher value than the target behind it.
I trust this article helped you get a much better understanding of skewers in chess. It is important to study patterns (also know as motifs). It will help you get a better understanding of how those patterns work in various situations.