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Michael McDowell & BDS

Problem Observer, 1992

#2
Circe

1.Ka2  (2.Qa1#)

1...Qe7 2.Qg1#
1...Qf8 2.Qd1#

In the diagram position White has two queen checks available, but neither of them is mate. 1.Qg1+? is not mate because of 1...Qxf4 (+wPf2)! [1...hxg1 (+wQd1) doesn't stop the check.] and 1...Qd1+? is not mate because of 1...Qxd7 (+wPd2)! Notice that the black queen is on the only square from where it can attack both the d-pawn and the f-pawn. The key threatens 2.Qa1# and Black can defend by attacking the wPb4 so that if White were to continue 2.Qa1+? Black could respond with 1...Qxb4 (+wPb2)! However, each move to attack b4 abandons an attack on either the d-pawn or the f-pawn and so White can then carefully choose the check which can no longer be interrupted by Black capturing a pawn.