The queen makes an outstanding defender of its king’s position; it can guard several squares at once, and can move in any direction if its services are required at the scene of an attack. It therefore is common enough to have the makings of what otherwise would be a good mating attack, only to find it frustrated by the enemy queen’s presence nearby. In these circumstances a simple attack on the queen may be enough to either drive it off or force your opponent to make a sacrifice to avoid disaster. This time we will separate conventional attacks on the queen from “flush” attacks, just for the sake of reinforcing each visual pattern independently.
We begin with positions where you threaten the queen and really don’t care if it takes your attacker; in fact, you hope it does.
Our inspection of this first position turns up not only a pin of the rook on g7 but more generally an attack by White’s rook and queen on the g7 square next to Black’s king: a mate threat. What prevents it from succeeding is Black’s queen on h7. The first urgent thing is not to let the presence of Black's queen prevent you from wondering about what would be possible if it were gone. The next thought, then, is to consider throwing an attacker at the queen. In his rook on d3 White has a piece he can use for the purpose without disturbing his mate threat. He plays 1. Rd3-h3. Now Black is in trouble. His queen is under attack and the rook aimed at it is loose, so the natural impulse is to play QxR—but then White mates with QxR. Yet the situation as it stands is untenable for Black, because now his queen is pinned and thus cannot defend g7 anyway (this would have been another way to see the solution, of course: trace the lines out from Black’s king and see a pinning opportunity on the h-file). So Black has to play 1. …Kg8, freeing his queen. This avoids the mate, but now Black still loses his queen to 2. RxQ. (Black is able to win back a rook by replying 2. …RxRg1+, 3. NxR, KxRh7, still leaving White with a winning material advantage.) In this case the attack on the guard of the mating square ends up winning it—one of several possible outcomes of such maneuvers, as we shall see.
Now also notice another way to reach roughly the same result. You see that you have a capture to make in 1. RxR that leads to QxR. You look for your next check, find 2. Rh3, and see that it forces Black to play Kg8. Now you see Black’s king and queen again aligned on the same file—and this time White safely can run a pin through them with 3. Rg3, where the rook takes protection from the pawn on h2. After Black plays QxR (avoiding mate), White’s 4. h2xQ wins him a queen for a rook.