putting Black in zugzwang. Black has six defences leading to three Grimshaws, one of them a pawn Grimshaw: 1...Rb7 2.Rc6# (2...Bxc6 not possible) 1...Bb7 2.Re7# (2...Rxe7 not possible) 1...Rg7 2.Qe5# (2...Bxe5 not possible) 1...Bg7 2.Qxf7# (2...Rxf7 not possible) 1...Bf6 2.Qg4# (2...f5 not possible) 1...f6 2.Qe4# (2...Be5 not possible) After other black moves, White can play one of the above moves to mate; the three exceptions are 1...f5, taking away that square from the king and allowed 2.Qd6# and two recaptures: 1...Rxc7 2.Nxc7# and 1...Bxd4 2.Nxd4#. Novotny A close relative of the Grimshaw is the Novotny, which is essentially a Grimshaw brought about by a white sacrifice on a square where it can be captured by two different black pieces – whichever black piece captures the white piece, it interferes with the other. References Further reading External links A selection of Grimshaw problems, including many fairy problems Chess problems