Prokes Ladislav,Duras Oldrich - White wins
Casopis cs. sachistu, 1921

Ladislav Prokes composed this windmill study together with one of the greatest Czech players, Oldrich Duras.

1.f4+ Kg4 2.Qg3+ Kf5
White uses the mill to get rid of the pawn on e5.

3.Qg5+ Ke4 4.Qxe5+ Kf3 5.Qe3+ Kg4 6.Qg3+ Kf5
Without the black pawn on e5, white has time for a quiet move, threatening mate.

[However, both Ivo Novak and Noam Elkies discovered a dual solution, allowing the white queen to swing in two directions: 7.Qxd3+ Kf6 8.Qc3+ Kf5 9.Qe5+ Kg4 10.Qg5+ Kf3 11.Qg2+ Kxf4 12.Qg3+ Ke4 13.Qe3+ Kxd5 (13...Kf5 14.Qf3++- ) 14.Qb3++- ]

[7...Qf6 8.Qg4# ]

8.Qg5+ Ke6 9.Qxg6# 1-0