Figure[White to move]

This position also combines our current theme with an earlier one. Black’s king is confined to the back rank by the knight on f5. White has two heavy pieces he can put on the rank—his queen and rook—but Black defends the squares they are able to reach with his rook, bishop, and queen. Meanwhile White’s queen attacks Black’s bishop and queen; and the queen’s only guard is the rook on b8.

That pattern should ring a bell—a piece you can take that is guarded only by a rook on its back rank. In such cases we have seen that dropping a rook of your own onto the back rank (with check) may drag the enemy rook out of position to fulfill its defensive obligations; here the idea for White would be 1. Rd8+, RxR; 2. QxQ.

Ah, but there is a catch: Black can reply to Rd8+ with BxR, leaving his queen still guarded. Yet look at the board that then results and see what the bishop does on its new square, d8. It blocks the rook’s path along the back rank and enables White to mate on the spot with Qe8. So Black has to reply to Rd8+ with RxR after all, forfeiting his queen to avoid mate.

There is another lesson to take away from the position. When your queen is one of the offensive pieces involved in this pattern, don’t forget multiple routes it may have to the enemy’s back rank—here not only Qc8 but Qe8. Once you see that both of those are potential mating squares, the power of planting a piece between e8 and the square's defender becomes more apparent.