Mate in 3

If not for the pin, pushing b6-b7 would mate at once. White’s plan, therefore, is to shake off this pin. However, attempting to do so directly falls short. Take 1.d4?, for instance. Black replies 1...Rb3+!, the rook barges in with checks, ruining any hope of a mate in three. The try 1.Rxa7? Nxa7 also runs aground, as Rb1 then prevents b7#.

The key is subtler: 1.Kf2! — a patient, non-threatening, almost deferential move, which leaves the pin in place but quietly sets the stage for its undoing on the very next turn. Black is now caught in zugzwang:

• 1...Rb2 2.Kg2! threat: 3.b7#

     2...Nxd6 (N-any) 3.Rxa7#

• 1...Rb3 2.e3! threat: 3.b7#

     2...Nxd6 (N-any) 3.Rxa7#

• 1...Rb4 2.d4! threat: 3.b7#

     2...Nxd6 (N-any) 3.Rxa7#

The three variations above illustrate the thematic unpinnings. Additionally, any random move of Black’s rook along the first rank — abandoning the b-file — such as 1...Rh1, allows 2.Rxa7+ Nxa7 3.b7#, while 1...Rf1+ in particular results in 2.Kxf1 (threat: 3.b7#) 2...Nxd6 3.Rxa7#.

A charming three-mover, light in touch and masterfully crafted by a true luminary of the genre!