Scan out from the Black king and you see that the knight on d7 is pinned. Size up the impediments to exploiting the situation: the knight is attacked twice and guarded twice, and White has no immediate way to bring more power to bear against it. What to do? Consider replacing the target with an exchange and ask what would then become possible. Sometimes exchanges simplify the board and so clear the way to bring in reinforcements. We have been looking at exchanges initiated by the pinning piece, but this time let's do it a little differently, starting with 1. RxN, RxR. The pinned piece has been replaced, and the new piece still is attacked once (by the pinning bishop) and guarded once (by the king). But this time White has cleared a way to bring in backup: Rh1-d1, and now Black’s rook is attacked too many times and gets taken on the next move.

We see here an example of the strength of coordinated (or “connected”) rooks. Sometimes one can replace the other, increasing the power directed at a target in unexpected ways.