White’s task is to reach the 8th rank, Black’s job is to stop that.
Click or tap on a move in the game text for a popout display board.
1. Ke6! wins, because after Black goes to one side 1…Kd8, White goes to the other side 2. Kf7 (or 1…Kf8 to one side, 2. Kd7 to the other side).
If not 1. Ke6!, White has seven alternatives. Six of them lose, while only one maintains White’s winning chances. I asked ‘which one of the seven alternatives to 1. Ke6 wins?’.
It’s 1. Ke4! Remember, the key position is Ke6 / ke8. If it’s Black’s move, he must step aside, and White wins by going to the other side. But if it’s White’s move — and White does not play 1. Ke6! or 1. Ke4! — Black holds him off directly (1. Kd5? Kd7!) or mirrors him from a distance (1. Kf4? Kf8!).
Look at what’s going on here: If White makes an odd number of ranks between the kings (1. Ke6 == 1; 1. Ke4 == 3), White wins. But if White goes to a side too soon, Black steals that odd-number advantage. These all win for Black: 1. Kd6? Kd8!; 1. Kd5? Kd7!; 1. Kd4? Kd8!
The important phrase is “White moves forward, moves forward, moves forward, until Black steps to a side. When Black steps to a side, then White cross to the other side.” What’s the winning procedure if we back all the way up to
1. Ke2
White moves forward.
1…Ke7 2. Ke3
White moves forward. Moving to the d- or f-file loses for White (the student should work this out).
2…Ke6 3. Ke4!
White moves forward, and if Black moves to one side 3…Kd6, White goes to the other side 4. Kf5 and wins. What if Black keeps to the e-file?
1. Ke2 Ke7 2. Ke3 Ke6 3. Ke4 Ke7 4. Ke5! Ke8 5. Ke6 Kf8 6. Kd7
Moving forward until Black steps to one side.
Now do this one. White to play and win.