Lessons From Munich: Aiding The Enemy

MY round-six game reached the following position after 45 moves.

Black has just played 45...a7-a5 in Spanton (1954) - RR Vasudevan (1932)

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I played 46.b4?, which helps Black by making it easy to create a passed pawn, and so the position changes from winning for White to completely equal, according to Stockfish17 and Dragon1.

Instead 46.f4 leaves White the equivalent of at least a minor piece ahead (Stockfish17) or even the equivalent of a rook ahead (Dragon1).

A sample line runs 46...Kc5 47.g5 Kd4 48.gxh6 gxh6 49.Kf6 c5 50.Kg7 Nd7 51.Kxh6 c4 52.bxc4 bxc4 53.Bxc4!? and wins.

LESSON: rival pawn-majorities in an ending are in a race to create a passed pawn, so taking time out from your own race to help the opponent reach the finishing line is just about the last thing you want to do.