Skewers in Chess
A skewer in chess is a maneouvre where you attack a high-value piece or the king of your opponent, with the aim of taking the piece behind it. Only those pieces that attack along lines, i.e. your queen, bishops and rooks, are eligible to perform skewers. The moving pattern of knights, pawns and kings makes it impossible for them.
If you’re aware of how pins work (check out our piece about pins, if not), then you can think of a skewer as the opposite orientation as a pin. In a pin, the high-value piece sits behind a lower-value piece, but in a skewer, the high-value piece is in front.
To get an initial impression of how a skewer works, let’s take a look at the following example:
Here we have the black bishop putting pressure on the white rook. White is likely to move the rook in this case - even if white can recapture the bishop, its lower value makes it a rather poor trade for white. Once white moves the rook however, black can then capture the knight on a1 and successfull execute the skewer.
As with pins and forks, there are broadly two types of skewers - relative skewers and absolute skewers. The difference between the two comes in whether or not the king is involved as the piece being attacked. A relative skewer doesn’t involve the king, but an absolute skewer does.
Absolute Skewers
As previously explained, an absolute skewer involves the king, and more specifically involves a check on the king. The aim of the absolute skewer is that the king moves to the side of the attacking piece to remove itself from check, and the attacking piece then takes the piece behind. Here’s a simple example.
In this scenario the black rook checks the white king. The white king now has a choice of which square to move to, but it must be out of the d file to escape from check. After the king moves aside, the black rook can then come swooping down to capture the white rook on d1.
This is a contrived example, but it’s not uncommon for this situation to prevent itself, especially during the end game when few pieces are left.
This is an absolute skewer for the simple reason that white has no choice but to avoid check and thus let the black rook take the white rook.
Relative Skewers
A relative skewer is one which does not involve the king. The piece being attacked is instead a high-value piece (or a low value piece that is unprotected) that then must move aside to reveal a piece behind it which the skewering piece can take.
Let’s see an example:
This is the same as the previous example with the difference that it’s no longer the white king under attack but the white queen. To prevent the capture of the queen, white would move the queen out of the way and therefore allow black to capture the rook, once more on d1.
Executing a skewer
In order to execute a successful skewer, there are a few points to take into consideration. Will your attacking piece be in danger of being taken when performing the skewer? If so, will you be able to protect it? Is the piece under attack of high enough value that it won’t be traded for your skewering piece. Is the piece being skewered behind of high enough value that it’s worth taking or trading with your piece? All of these questions need to have good answers before embarking on a skewer maneouvre. Let’s see some example of good and bad skewers.
Here we’ve got black skewering white’s rook and bishop. It’s clear that white will want to move the rook in this scenario (not sure why that? Check out this post on piece values.) But is it worthwhile? Assuming either b1 or a2 are available for white to move the rook into, then this skewer has just become a bishop trade. Unless black has a good reason to make that trade, this isn’t a great example of a skewer.
This scenario is actually even worse for black. In attempting to skewer white’s bishop and queen, black is risking losing the bishop altogether for no compensation whatsoever. The bishop doing the skewering is at risk of being taken by white’s queen. Since white has the bishop to back up and protect the queen, should black wish to capture the queen, it would merely be a queen trade at that point, and, after losing the bishop in the first place, would likely make for a pretty disastrous skewer. Instead of gaining some sort of advantage, black is now down a bishop - a potentially significant disadvantage.
Here’s a similar skewer, but a bit more successfully executed.
By switching the white bishop in our previous example for a white rook in this one, this now becomes an extremely effective skewer. Most importantly, black has protected the bishop from the white queen. Should the white queen choose to capture the bishop now, black will recapture the white queen, which would be an excellent advantage for black at that point, having traded a lowly bishop for the opponent’s queen - a great piece of business as far as black is concerned. Due to this, white is unlikely to take the bishop and would likely instead opt for moving the queen out of harm’s way, exposing the rook behind. Regardless of whether or not the rook is protected, this then becomes an advantageous situation for black. If the rook is unnprotected - and white cannot cover it with the queen once the queen moves - then black can extract the bishop and have captured a rook for no sacrifice, yet again a fantastic piece of business for black. Even if the rook is protected, trading a bishop for a rook is a good trade for black and would present black with a materical advantage from this point on.
Escaping from a absolute or relative skewers
There are a couple techniques to escape from a skewer that are effective for both absolute and relative skewers:
- capturing the skewering piece
- moving a low-value piece to intervene in the skewer
The first of these requires little explanation. Capturing the skewering piece eliminates the threat and provides relief from the skewer. If the skewering piece is protected, then this works well if you can capture with a lower value piece. Let’s see an example of that in action:
The black bishop is once again skewering the white rook and the white bishop behind it. Fortunately, the white knight is on hand on d3 to take the bishop and remove the threat of the skewer. This would be a trade in this case, since black would recapture the white knight with its own knight on g6.
Alternatively, if a piece can come between the skewering piece and the skewered pieces, this can be a welcome respite from the skewer. In live game situations, pawns often provide such cover from the skewer. The escape comes with the caveats that the intervening piece be both protected and of a lower value or equal value than the skewering piece. Let’s see a quick example.
In this scenario, white’s pawns are coming to the rescue. With the pawn on d2 for cover, the white pawn on c2 can be pushed up to c3 to block the bishop from the rook. Black would be foolish to trade the bishop for a pawn, so this skewer has been effectively dealt with.
Escaping from relative skewers
In the case of a relative skewer, there are a few more options open for escaping from even the best skewers:
- checking the opponent with either of the skewered pieces
- threatening a high-value piece with either of the skewered pieces
These two escapes are similar - the distinction is the same as the distinction between absolute and relative skewers. The first option, checking the opponent forces them to make a move to get out of check, and with the following move, move the other skewered piece to safety.
Another potential benefit of this option is that it has the potential to become a discovered attack. Without going into too much detail about discovered attacks, let’s see an example of this in play.
In this scenario, white can get out of the skewer by moving the rook to b7 or f2 and checking the black king. This has the added benefit that the white bishop is now also attacking the black bishop, and once black moves the king to escape the check from the rook, white can capture the black bishop. This discovered attack makes the escape from the skewer especially nice for white, as it’s taken a dangerous situation and reversed it to put pressure on black and even gain an advantage.
Threatening a high-value piece is a similar escape but comes with similar caveats to executing a relative skewer. If we switch out the king in the previous example for a queen, we can see that a similar escape is on offer for white, but it’s less foolproof and can be more easily countered by black.
White can once again move the rook to b7 or f2 to put pressure on the black queen, but now the story is a bit different. Black, if the rook is unprotected, would be in a position to take the rook and sacrifice the bishop, meaning the escape attempt was unsuccessful. Black could also have the chance to check the white king with the queen, removing itself from the line of attack of the rook and then capturing the bishop on the next move. The number of scenarios is countless, but the crucial issue is that there are more things to consider with this escape than with the previous one.
That just about sums up this piece on skewers. Used properly and they can be a great way to gain an advantage over your opponent, but be careful of the many pitfalls that can make skewers backfire very quickly.
If you have any comments, feedback or questions about anything in this post, leave them below.