Figure 2.2.10.5[White to move]

Here is a more challenging one. Black has no loose pieces except his rooks, which are tucked out of danger, and White has no checks to give. The most likely way to see the chance for a double attack here is to experiment with captures and their consequences. There is just one possible capture here for White: Nxd5, which more or less requires Black to play c6xN. Then how would the board look? What checks would then be available? Answer: Qb5, which would attack the bishop at b4 as well as the king. The bishop is protected by Black's queen. But it also would already be attacked once by the White bishop at d2 (remember that when you think of Nxd5, you imagine the knight gone from its current square and see the open lines that result). So the Black bishop would be as good as loose: after Black moves his king in response to Qb5+, White plays BxB and Black dares not recapture.

The tricky part of this example is seeing the potential for a double attack at all, since none of the ingredients are visible at the start. But even from the beginning you might notice a basic pattern that is familiar by now: by moving to b5 the queen would be aimed at the enemy king and would have Black’s bishop just underneath it. Double attacks by the queen often look like that. It doesn’t quite work yet because the pawn at c6 blocks the check and protects the needed square, and because the bishop is protected once and not yet attacked at all. Still, if you can see the rough outlines of the familiar pattern, you can then play with various forcing moves on the board, like Nxd5, with a view to making the queen fork effective.

You also might see the tactical idea here by first observing that Nxd5 is a knight fork of Black’s queen and bishop. Since the Black bishop would also then be attacked once by White’s bishop, the knight fork is a real threat to Black and must be met with c6xN. This then becomes a problem similar to the knight forks we already studied where you imagine playing the attack knowing that it will fail when your knight gets taken; you ask what would then be possible, and particularly what checks you would have available. Here that inspection would turn up a check by the queen which also attacks the bishop for the second time.