Last week, we looked at a chess tactic called a skewer. A skewer is similar to a pin. Only the long distance pieces – Queen, Rooks and Bishops – can execute a skewer. Skewers also take place along the ranks, files or diagonals. Like a pin, three pieces are involved in a skewer; the piece performing the skewer, the skewered piece and the piece behind the skewered piece. The difference between the pin and the skewer? In a pin the more valuable piece is behind the piece being pinned. In a skewer, the the less valuable piece is behind the more valuable piece being skewered. When the more valuable piece moves, the less valuable piece is captured. However, there are a few caveats to consider before trying to create a skewer.
Whether you’re employing a pin or a skewer, you need to carefully consider the value of all the pieces involved, including those of your opponent. Let’s look at your opponent’s pieces first. Two of the three pieces in a skewer belong to your opponent, the piece being skewered and the piece behind it. The whole idea behind the skewer is that one of your pieces attacks a more valuable piece belonging to your opponent and, when that more valuable piece moves, your piece captures the less valuable piece behind it. For this to work, the piece doing the skewering has to be worth less than the more valuable piece being skewered. The piece doing the skewering also need to be protected.
These two caveats are where beginners get into trouble. One of the reasons that I force the relative value of the pawns and pieces into my students thought process from day one of class is because without a knowledge of relative value, you’re apt to make lopsided trades or exchanges. The relative value system denotes the power each of your pawns and pieces has. The greater the value, the greater the power. The pawn has the lowest relative value (one) because it is the most limited member of your army in terms of attacking abilities (except when a pawn is about to safely promote). On the other side of the spectrum is the Queen, who has the highest relative value (nine) because of her ability to attack the greatest number of squares simultaneously. So what does relative value have to do with a skewer? EDIT
Skewers employed before the endgame generally end up with the player doing the skewering exchanging the piece that performs the skewer for the opposition piece at the other end of the skewer. When this takes place in the middle-game, the opposition piece that gets captured, after the more valuable skewered piece moves, is defended. This means that the player executing the skewer will then trade material. Set up the following position on a chessboard: Place a Black Bishop on h8, a Black Rook on f8, the White Queen on b2 and a White Rook on a1. It’s White to move (don’t worry about having Kings on the board because this is simply an instructional example). Black’s Bishop is skewering the White Queen on b2 to the Rook on a1. If White leaves the Queen on b2, the Black Bishop will be able capture it free of charge. It’s important to note that the piece doing the skewering, the Black Bishop, is worth less than the White Queen and Rook. This makes the eventual exchange advantageous for Black! If Black had instead used his Queen to Skewer White’s Queen and Rook, Black would lose material after the exchange. Due to the Black piece doing the skewering being worth less than White’s material, White will move the Queen. Where? To a square that allows it to defend the White Rook, such as a2. Black would then play Bxa1 followed by White playing Qxa1. Defending the Rook reduces the material loss for White. What if Black didn’t have the Rook on f8 to defend the Black Bishop on h8?
This brings me to the idea of defending the piece doing the skewering. If it was White’s turn and there was no Black Rook on f8 to defend the Black Bishop on h8, White would simply capture the h8 Bishop and win material. You need to defend the piece doing the skewering. Beginners tend to execute skewers without considering this, which leads to an absolute tactical failure. You ideally want to use a piece of lessor value to skewer pieces of greater value and make sure your piece doing the skewering is protected!
Next week, we’ll end our examination of the skewer by looking at a type of skewer that garners the best material results, skewers involving the King. A homework assignment I give to my students is to set up random positions on the board involving the three pieces that can execute a skewer – the Queen, Rook and Bishop – and trying to create skewers. Place a White Queen, Rook and Bishop randomly on the chessboard. Then, place a Black Queen, Rook and Bishop randomly on the chessboard. Start with White to move. See if you can find a potential skewer and play it through. Do the same for Black. The idea is to get your brain trained to recognize tactical opportunities through pattern recognition and develop you ability to find combinations of move that create tactics (we’ll look at combinations in a few weeks). Here’s a game to enjoy until next week!