Sometimes the purpose of a check is not to drive the enemy king away from its protectorate, but rather to draw it away by forcing it to capture the piece you have used to attack it. This procedure is known as a decoy. It necessarily involves a sacrifice, often of a rook, and so is most often used to enable the capture of an enemy queen, but we will see other uses of the principle as well. The logic of the move and the means of searching for it really are no different than before. You still are looking for checks that will move the enemy king away from a piece that it guards. It’s just that this time the check is given by a piece that you plant flush against the king, with or without a capture. In prior parts of this series we have considered these checks interchangeably with others. We are examining them separately here because our focus now is solely on ways of removing the guard, and decoys—checks that invite the king to capture—are a common and important technique for this purpose worthy of a few moments of undivided attention.
The position to the left is a simple example. What does Black threaten? His queen attacks White’s queen, which in turn is protected by its king. A piece protected by its king invites consideration of a check to drive the king away; and when the protected piece is a queen, the prospect of capturing justifies a flush check that allows the king to capture the threatening piece. Here Black has the most common resource for such a purpose: a rook, which he plays to h1. White’s forced reply is KxR—leaving his queen loose, and losing it to QxQ next move.