Study by Johann Behting

When I posted this position two days ago on Facebook, it reached thousands more people than is usual for my high-performing posts, but elicited very replies with the correct move. There were responses, but most failed to observe the critical move--the only one that maintains a winning advantage.

White to move

According to Harold van der Heijden, Endgame Study Database VI, the study was published in Rigaer Tageblatt, a Riga newspaper. The composer is Johann Behting (1856-1944). His brothers, Karl and Robert, also published studies. When I encountered* this study in The Manual of Chess Endings by Sarhan Guliev on Sunday, credit was given to Karl and Johann with a date that was clearly incorrect (14). Guliev has 1984, while van der Heijden has 1894. The one in Guliev is one move earlier. Both appear in Endgame Study Database VI.

White to move

I contemplated my solution while eating breakfast, then set it up on my iPad to play against Stockfish. Although 1.Ke4 looked forcing, I could not see clearly to the end and opted to push a pawn first, instead--the wrong pawn, it turns out. Nevertheless, I prevailed against the engine.

1.f7 Ke7 2.Kf3!

As in the first position presented above, this move is the only one that wins.

2...c6 3.Kf4! c5 4.Ke4!

White moves to this square only after Black's c-pawn has advanced to c5, although it also can be played before advancing either White pawn. The computer's line reaches the same position that I did at move 8 (below).

4...Kf8 5.Kf5

Threatens checkmate.

5...Kg7 6.Ke5 d3

White to move

7.Kd6! d2 8.Ke7 d1Q 9.f8Q Kg6

Every move I've played after the first has been an only move.

White to move

I did not get the sense that my play from this point was the best, although it was good enough. After two more efforts from the beginning on my iPad, I spent some time evaluating the first effort on my computer.

In my second effort against Stockfish on the iPad, I started with the e-pawn, hence reaching the position in the other study after one move.

1.e7 Kf7 2.Kf3 c6 3.Kf4 d3

White to move

Stockfish chose the longest line to checkmate, I thought, but this choice made the rest of the exercise too routine. According to tablebases (the iPad app does not access these), both 3...d3 and 3...c5 lead to mate in 16. Only 3...c5, however, tests a human's skills above an elementary level.

On the third effort, I helped Stockfish a bit (switching sides) to get a chance to play the critical line against the app.

3...c5 4.Ke4 Ke8 5.Kd5 Kd7

White to move

6.Kc4! Ke8 7.Kxc5 Kd7

Here, 7...d3 strikes me as more testing. 8.Kd6 d2 9.Ke8 mates with a pawn, and concludes as in the solution given by Guliev.

8.Kxd4

The rest is simple.

*Note: After starting this post, I discovered that I had previously written about this study in "Two Endgame Compositions" (2016). Questions that I had then, I still have.