Breakthroughs
White has a K-side pawn majority of two to one.
Capablanca's rule states that you start mobilizing a pawn majority by pushing the unopposed pawn, the one with no enemy pawn ahead of it on the same file.
This generally eases the creation of a passed pawn. But that startegy fails here: 1.g6 hxg6 2.hxg6 Kf6 3.Kh5 Kg7, and the pawn is blockaded.
Or, 1.g6 hxg6 2.h6 Kf6 3.Kh4 Kf7 4.Kg5 Kg8 5.Kxg6 Kh8, with a positional draw.
To win, White defies the rule and pushes the opposed pawn instead, 1.h6. After 1...Ke6 2.g6 Black cannot stop White from promoting at h8.
