Endgame Series 24 - Opposite-colored bishops
Hello, Dear chess friends!
In Endgame series issues #18 and #19, we covered in-depth opposite-colored bishops endgames. We looked at many instructive practical examples and formulated a number of important conclusions with the theoretical value. I listed these conclusions right below this introductory passage. We will loosely refer to them as ‘principles’ (e.g. ‘’White followed principle 3’’, or ‘’Black forgot about principle 5’’…) for easier reference, as we explore new examples with opposite-colored bishops endgames in this issue of Endgame series. Most of these examples have been taken from very recent top-GM practice.
Principles of opposite-colored bishops endgames:
1. Weaker side often has drawing chances being one, two, or sometimes even three pawns down.
2. Drawing chances usually arise due to the blockade.
3. Drawing chances sometimes arise due to the wrong-colored bishop (rook's pawn) and, more rarely, stalemate.
4. With two passed pawns which are three or more files apart (i.e. f- and b-; g- and c-) the stronger side usually wins; with two passed pawns two or fewer less apart (i.e. e- and b-; g- and d-) it is usually a draw (there are some exceptions).
5. Winning chances increase as two passed pawns are further (more files) apart.
6. In the case of pawn races, it is critical that the attacker's bishop can simultaneously protect its own passed pawn and block the opponent's passed pawn; otherwise defender's drawing chances increase significantly.
7. Winning ideas for the stronger side: Penetrating with the king, Pawn breakthrough, Overloading defender's bishop, Improving the position of the bishop, Zugzwang, etc.
8. King's penetration is a crucial strategy for the stronger side and for that purpose he has to be ready to sacrifice pawns or even the bishop.
9. It is often difficult to win based on one weakness only (such as an outside passed pawn), so it may be necessary to create the second weakness, usually on the opposite flank.
10. Defender's chances increase if his bishop can block two passed pawns on a single diagonal.
11. Defender's chances increase if his king can block the penetration of the opponent's king by moving diagonally, rather than vertically or horizontally.
12. "Two-on-one" pawn breakthrough sacrifice is a standard maneuver to create a passed pawn and improve winning chances.
13. In principle, the defender should avoid putting his pawns on the color of the opponent's bishop (there are exceptions, sometimes).
14. Mutual weaknesses and asymmetrical pawn structure usually favor the stronger side.
15. When the stronger side has a passed pawn on rook's file and a wrong-colored bishop, the defender should look for a way to get his king in the square of that pawn and try to liquidate into a B + 2p vs B endgame, which is drawn because the bishop can always be sacrificed for the second pawn.