Now consider another variation on our theme: a potential fork is frustrated by a piece lying between the forking square and one of the targets—the king or the loose piece. Again much of our attention will be devoted to the process of noticing such situations; once they are found, standard tools—threats and exchanges—often can be used to resolve them.
The most important general skill here is the ability to see “jump checks”: moves that would give check if some piece (perhaps an enemy piece, or perhaps one of your own) weren’t in the way. These are important to see generally, and they are especially important if you have found a loose enemy piece. For then you turn all your efforts to looking for a way to attack the loose piece and give check at the same time, and you don’t want to overlook a check just because there is a piece that would need to be gotten out of the way before it can work. The best way to find checks like this is to try just aiming pieces at the enemy king. If pieces of your own are in the way, look for time-consuming threats you can make by moving them. If your opponent’s pieces are in the way, try to force them off their squares with threats or by taking pieces they protect.
In this first example to the left, look first for any loose enemy pieces. Here Black’s rook is loose at d7. Can White’s queen attack it and give check at the same time? No, not yet. But if the queen moved to g4 it would be aimed at both king and rook; thus only the Black pawn at g7 prevents a successful fork. So ask whether White can draw that pawn out of the way by taking something it protects. The g7 pawn guards the bishop at f6, which White can take with his rook. So 1. RxB, g7xR; 2. Qg4+ gets the Black rook and wins a piece.