Figure[White to move]

The role played by the light-squared bishop in the previous frame also can be filled by a rook. The point is the same: taking out the h7 pawn with a sacrifice that leaves the way open for an attacker on the h-file. The diagram to the left illustrates the idea. The important thing to see is that White’s rook on a1 is ready to participate in a mating attack; any rook or queen that can get to the h-file in one move is poised to help you mate, no matter how far away they may appear to be. In this case play goes 1. Rxh7, KxR (otherwise White plays Rh8#); 2. Rh1+, Kg8; 3. Rh8#.

Notice that in the positions so far Black’s g-pawn has been moved forward from its original square. That is what makes these checkmates go: once that pawn moves, White’s dark-squared bishop has an open path to h8; these patterns then spring to mind. This signature should help you spot the idea when it is available; it also should give you pause before moving your g-pawn.