Now we consider a single rather common pattern. Sometimes a rook on the back rank will protect a piece that lies somewhere up the board on the same file. This can be a perilous arrangement, because a rook so positioned often is needed as well to protect its king against attacks on the back rank. Such a rook quickly can become overworked. Here we examine this theme and variations on it in some detail.
This first diagram presents the point in simplest form. White has the power to capture Black’s queen with his own, but the Black queen has protection from its rook at b8. When you see a piece drawing protection from a rook on the back rank, ask whether you can make trouble elsewhere on the back rank—as with a check like Rc8+. Black has no flight squares for his king, so his only legal reply is RxR. This leaves his queen loose and so allows White to play QxQ. Black’s rook was overworked; it protected its queen and also the mating square c8. (Notice, of course, that the reverse move order ends in disaster for White, as the Black king gets a flight square on g7.)