This is a fascinating position. Despite the bishops of opposite colors, Black is hard pressed to stop the White c-pawn from promoting. The pawn at a5 is under attack, but there is no time to capture it because the bishop cannot get back to stop the cpawn. 30...Kf7 [ 30...a4 loses to 31.c6 ] 31.Bxa5 Ke8 32.c6 Bd1 33.c7 Kd7 White advances the cpawn to tie down the enemy king. Black needs to keep the bishop active to be able to defend the two weak e-pawns. Since all of White's pawns are on dark squares, Black has no targets, and therefore no counterplay. 34.Ke1 Ba4 35.Kd2 Bc6 36.Kc3 Bb7 37.Kd4 Bc6 38.Kc5 Bb7 39.Kb6 The point of this king journey is simply to free the bishop and provide support for the advance of the a-pawn. Kc8 40.Bb4 Bd5 41.g4 This insures that Black cannot try to defend with ...h5, ...g6 and ...Bf5. [ 41.a4 Kd7 42.a5 Kc8 43.a6 Kd7 44.a7 Kc8 doesn't accomplish much. The key to the win lies on the kingside. White patiently prepares the way. ] 41...Kd7 42.h4 Kc8 43.a4 Kd7 44.a5 Kc8 45.a6 Kd7 The queenside pawns cannot be promoted because Black has all the light squares under control.
However, should the Black king be forced to c8, White may be able to get the king to d6 and from there the kingside can be infiltrated. 46.Bf8 g6 47.g5! The pawn at h7 is permanently crippled. Kc8 48.Bb4 Kd7 49.Ba5 The point of the bishop maneuver is to defend the pawn at c7 while keeping d6 open for the king. Kc8 50.Kc5 Kd7 51.Bb6 Ba8 Black has been reduced to shuttling the bishop between d5 and a8. The a-pawn was kept on the sixth rank to control b7. White now winds by deflecting the king from d7. 52.c8Q+! Kxc8 53.Kd6 Bd5 54.Ke7 A highly instructive endgame, showing the importance of playing both flanks in a bishops of opposite color endgame.