The opposite-colored bishops endgame refers to a scenario where each player has only one bishop, and the bishops are positioned on squares of different colors. When there are no other pieces except pawns on the board, such endgames are notoriously difficult to win and often result in a draw. Even when one side has a slight material advantage, it can be challenging to convert it into a victory. If there are additional pieces on the board, the player with a stronger position has a better chance of winning, but not as much as when the bishops are placed on squares of the same color.
Edmar Mednis, a Latvian-American grandmaster, proposed two principles that can be applied to endgames where the bishops are positioned on squares of different colors:
- If a player has a material disadvantage, they should try to find opportunities to force a draw in an endgame with only bishops and pawns.
- When major pieces such as a queen or a rook are present on the chessboard, having opposite-colored bishops is generally favored by the player launching an attack.
As a consequence, even if one player has a material advantage of two or three pawns, the game can still end in a draw. This is because the weaker side can establish a blockade on the squares controlled by their bishop, preventing the stronger side from making any significant progress towards a win.
There are further principles, outlined by an Australian grandmaster Ian Rogers, that players can follow in endgames where only the bishops and pawns remain on the chessboard:
- Having two connected pawns is usually not enough to secure a win unless they manage to advance to the sixth rank.
- When an attacker has two passed pawns that are far apart from each other and cannot be controlled by the opposing bishop on a single diagonal, they typically have a strong chance of winning the game.
- When the attacker has an outside passed pawn, it should be stopped by the bishop only when the king can block the opposing king.
That’s some theory, isn’t it? I think it’s a good time to show real examples. For the most endgames of this kind, let’s remember the fundamental rule: If you are defending against just one pawn, have your king block the opponent’s pawn from a square that cannot be attacked by the opponent’s bishop. 99% of such situations end up as draws, as the attacker cannot push your king away, so all you have to do is to make endless moves with your bishop.
Situations with two pawns on the attacking side are more interesting. Let me describe the most typical ones.
Example 1 – Connected pawns
This is an exemplary situation where even a material advantage of two pawns isn’t sufficient to win the game. See how the king and bishop can cooperate to block both pawns.
Example 2 – Doubled pawns
Doubled pawns are generally weak, and this endgame is no exception. Basically, the strategy is the same as if the attacking player has only one pawn, as the other one is of no help. The endgame is a draw.
Example 3 – Isolated pawns
There is another simple principle for isolated pawns. The more widely separated they are, the better the winning chances. In this case, the pawns are just too close to each other, and the endgame is a draw.
The rationale behind this strategy is that when the two passed pawns are positioned further apart, the defending king must block one pawn while the bishop blocks the other, allowing the attacking king to support the pawn blocked by the bishop and potentially win a piece. However, if there is only one file between the pawns, the defending player can typically prevent their advance.
Example 4 – More isolated pawns
When the isolated pawns are more separated, the winning tendencies of the attacking player are much improved. See the same position as before, but we moved the white pawn one square to the right. White wins.
There are exceptions to the rule of isolated pawns. Sometimes the defender can set up a blockade, especially if one of the pawns is the wrong rook pawn (TODO: article link). But I would say the general idea is clear.