One thing I like about searching for positions is that you often find instructive examples of things you weren’t looking for. Here’s one such gem of a find: a game with many twists and turns, and a survey of some of the main ideas in king and pawn endings as they apply to scholastic chess.
Black is about to have the chance to demonstrate the concept of an outside passed pawn: a passed pawn away from the rest of the action that can be used to distract the enemy king. (For anyone new following along: a passed pawn is a pawn that cannot be stopped by an enemy pawn). 39…exf4+! So far, so good: Black creates an outside passed pawn on f5. 39…e4? might look tempting. After all, it creates a protected passed pawn. The problem is that in the resulting position, Black’s king has no route into White’s territory. 40.Kd4! Kd7 41.Ke3 Kc6 42.Kd4 and the game is a draw. 40.Kxf4 Kd5!
Excellent! By abandoning the pawn at the right moment, Black prepares to take the White pawns on the queenside. 41.Kxf5
41…Kc6? But what is this? The white pawns were there for the taking! Black must have miscalculated something. I have a feeling they were in extreme time trouble. 41…Kc4! would carry the plan to its logical conclusion. 42.Ke5 Kxb4 43.Kd6 a5! wins by taking the a- or c-pawn next, depending on what White does.
44.Kc7 Kxc5 45.Kxb7 Kb4 followed by Black taking on a4 and queening their a-pawn. This is how the game was meant to end! Instead, we return to the action following Black’s blunder.
42.Ke5 the good news for Black is that all is not lost; they can still save a draw with correct play. 42…b6? This leaves Black without any way to get the remaining White pawns, and the 2 vs. 1 pawn ending is lost. 42…a5! would quickly exchange all the remaining pawns: 43.bxa5 Kxc5 44.Ke6 Kb4 45.Kd6 Kxa4 46.Kc7 Kxa5 47.Kxb7 is a likely finish. 43.cxb6 Kxb6 44.Kd5 Kb7 46.Kc5 Kc7 brings up another instructive moment.
Now White can win by using the concepts of opposition and outflanking. Right now, the kings are in direct opposition, separated by one square along a file. Whoever has to move first will need to give way. The side who does NOT have to move has the “opposition”, which both players want.
The players want opposition for different reasons. White, who is trying to win, wants the black king to give way. At that point, White will execute an ‘outflanking’–going diagonally forward in the opposition direction the enemy king retreated to, thus invading Black’s position.
Black wants the opposition so that when the white king moves to the side, Black’s king can follow it, blocking it from entering.
46.a5! is the winning idea. White has the opposition and Black must give way with their king allowing the white king to enter. 46…Kb7 47.Kd6 outflanks. From here the white king easily captures Black’s remaining pawn: 47…Kb8 48.Kc6 Ka7 49.Kc7 Ka8 50.Kb6 followed by taking the pawn and winning with 2 pawns vs. 0.
46.b5? was played instead: This is the opposite of what White wants! Now Black can trade down into a drawn king and pawn vs. king position.
46…axb5 would be the simplest draw from my perspective. 47.axb5 (47.Kxb5 Kb7 leads to king and rook pawn vs. king. If the defending king can block the pawn, as it does here, the attacker can never dislodge it due to the possibility of stalemate.) 47…Kb7 is a classic drawn king and pawn vs. king situation. To win, White would need to get his king to the sixth rank in front of the pawn, which Black is not allowing.
48.b6 Kb8! By retreating straight back, Black ensures that they will be able to block the White king. 49.Kc6 Kc8 Opposition. White has nothing better than giving stalemate with 50.b7+ Kb8 51.Kb6.
But as you may have guessed by now, that’s not what happened! As a reminder, we are in this position:
Black went for 46…Kb7 instead. This wouldn’t be my choice, but it doesn’t actually give away the draw. Then 47.b6 looks like a good draw, but is still a draw. That said, Black needs to be careful! 47…Kc8 48.Kb4 is a key position.
White wants to play Ka5 to win the pawn on a6. At the exact moment White plays it, Black needs to be able to respond …Kb7 to protect the pawn. These squares (a5 and b7) are called “mined squares”. If Black errs and goes to b7 when White can go to a5, White’s move sets off the mine: Black would be in zugzwang and White wins. 48…Kb8! saves the draw. The idea is that Black stays in the vicinity of b7, ready to answer Ka5 with …Kb7. (48…Kb7? 49.Ka5 would lose).
We return to the game, where there was one more twist in store:
White played 47.a5 with what I like to imagine was supreme confidence. In the ensuing position, where every legal move preserves the draw, Black resigned! Taking on b5, with the king and rook pawn vs. king draw, would have been the simplest choice.
If you would like to go deeper into any of the king and pawn endgame concepts discussed here, there are many great sources to explore. As a starting point, I would recommend the king and pawn endgames in the Learning Chess Step 2 and Step 3 Manuals, or the material in Silman’s Complete Endgame Course.