Now a well-known moment from Anderssen-Zukertort (1869). The most important feature of White’s position is his pawn on g7. It can function there a little like a bishop, ready to support mate on h8 and sealing off the Black king’s flight squares there and on f8. It has protection from the rook on g3; indeed, if it were a bishop White would mate quickly by withdrawing it and discovering check. Anyway, the question here, as in the previous studies, is whether White can get a heavy piece onto h8. As resources for the purpose he has his queen on h6 and two rooks on the g-file. Do you see anything else he can use? There also is the bishop on d3, which is aimed at h7 and can attack the square if the pawn on f5 steps forward to unmask it.

So White experiments with ideas. He starts 1. Qxh7+, KxQ—a massive sacrifice, but when you are trying for mate you don’t care. Now he imagines 2. Rh3+, and then 2. …Kg8, 3. Rh8#. That sequence would work fine were it not for Black’s queen on d6, which can interpose on h6 after White plays Rh3+. White still can force an eventual mate from the resulting position, but it gets messy, so Anderssen did it differently. With his second move he played the marvelous discovered check f5-f6+—using the bishop to force the king back to g8, and blocking the Black queen’s path to the h-file with his pawn. Let’s look at the resulting position....