Chess Puzzle

Enjoy today's puzzle:

There is an absolutely unanswerable move in this position. White found it, Can you?

Here is the solution to yesterday's puzzle:
Study by O. Duras
(Ceskoslovensky Sach, 1927)
First let us look at some wrong ways of playing (a) 1.Kb7 Kd2 2.Kc7 Kxe2 3.Kd7 Kf3 4.Kxe7 Kf4 5.Kxf6 and White wins easily. Here both players have played badly; so let us improve Black's play, since he lost. (b) 1.Kb7 Kd2 2.Kc7 Ke3! 3.Kd7 Kf4 4.Kxe7 Kxf5 drawn. So. (c) 1.Kb6! Kd2 2.Kc5 Ke3! 3.Kd5 Kf4 4.Ke6 Ke4 (4...Kg5 5.e4) 5.e3! and wins - Black must move with fatal results. But maybe Black can do better? Yes. (d) 1.Kb6! Kc3! 2.Kc5 Kd2 3.Kd5 Ke3 4.Ke6 Kf4 5.e3+ Ke4 Now it is White's move - not Black's as in (c) - and he must play 6.Kxe7 Kxf5 Drawn. So Black's subtle manoeuvre Kc3-d2 gained him a tempo. So it is drawn? No - White too can gain a tempo and we get the correct play (e) 1.Kb6! Kc3! 2.Kc5 Kd2 3.Kc6! Ke3 4.Kd5 Kf4 5.Ke6 Ke4 6.e3! and wins. In the final situation here, when the Kings are opposite each other with one square between them and Black has to move away, White is said to have "gained the opposition", gaining the opposition is a central element in King and Pawn endings and manoeuvres in this study to gain (or lose) tempi are characteristic of there endings.

Sorry for the long-winded solution I will be more selective in future. It is worth going through though for it's instructional value.