Lesson 11: Skewer and Discovery
A skewer is a situation in which one of your ranged pieces attacks one of your opponent’s pieces that is in front of another one of their pieces. When you skewer two pieces, you will be guaranteed to capture one of the two pieces.
In Diagram A, sente’s lance skewers white’s bishop and rook. If gote tries to save his bishop with ?B-44, then sente can take the rook with ?Lx52+. If gote doesn’t respond to the skewer, then ?Lx55 captures the bishop.
Can sente skewer the two pieces even if the rook is in front of the bishop? The answer is yes: with the help of the pawn on 57, sente can play ?L*56 and skewer the rook and bishop. Even though gote can play ?Rx, ?Px takes the rook back, so you have still succeeded in capturing one of the pieces. If gote lets the rook escape, ?Lx53+ takes the bishop.
Skewers are possible with all ranging pieces. In Diagram C, the bishop skewers the gold and knight.
Just like the fork, be careful for situations that look like skewers but allow the pieces to escape.
In Diagram D, it looks like the bishop and rook are skewered; however, gote can play ?B-37+, checking the King. After the King escapes, ?Rx56 wins the lance for nothing.
A discovery is similar to a skewer, but it involves having a ranging piece behind one of your own pieces. In Diagram E, sente’s bishop and gote’s rook are both in the lance’s path. Sente can make a “discovered attack” by playing ?B-24, checking gote’s king. By taking advantage of gote’s vulnerable position, sente’s lance is now attacking gote’s rook. Because gote is in check, he can’t save his rook, so sente wins the rook for free.
Discovered attacks don’t have to involve checks. In Diagram F, sente can play ?B-32+, attacking the gold on 23. This move also causes a discovered attack on the 72 gold with the rook.