Opposite-Colored Bishops
Opposite-Colored Bishops
Definition
The term opposite-colored bishops (often shortened to “OCBs”) describes a position in which each side still owns one bishop, but those bishops travel on squares of different colors—one bishop is confined to the light squares and the other to the dark squares. Because bishops can never switch the color of the squares on which they move, the two pieces can operate almost independently of each other, often creating highly unbalanced strategic and tactical situations.
How It Arises
Opposite-colored bishops typically appear after:
- An earlier exchange of one pair of bishops (e.g., BxB) leaving the remaining pair on opposite colors.
- Pawn structures that lock one color-complex, forcing an eventual trade of the “bad” bishops.
- Openings such as the Sicilian Dragon, Catalan, French Tarrasch, and many gambit lines where Bc5 or Bg4 is exchanged early.
Strategic Significance
The presence of OCBs changes the value of many other pieces:
- Endgames: With few pieces left, OCBs notoriously favor the defender. Because each bishop controls only half the board, it is difficult for the stronger side to create zugzwang or a mating net; passed pawns on the bishop’s “wrong” color may be impossible to shepherd through. Roughly half a pawn of theoretical advantage is often not enough to win.
- Middlegames: With queens and rooks still on, the same independence of color complexes can produce explosive attacking chances. You may see both sides simultaneously launching mating attacks that scarcely interfere with each other. Garry Kasparov once quipped that “opposite bishops are for either drawing or mating.”
Typical Plans
- Attacking Side
- Open lines on the color of your own bishop.
- Sacrifice material to destroy the opponent’s king shelter of the same color.
- Plant an unassailable bishop on a central outpost (e6, d5, etc.) that paralyses the enemy.
- Defending Side
- Blockade critical squares on the color not covered by the attacker’s bishop.
- Trade heavy pieces to head for a textbook OCB endgame.
- Create a “fortress” by fixing pawns on the color opposite the attacker’s bishop.
Classic Examples
Visualize or replay the following positions to feel the contrast in evaluation:
-
Fischer – Petrosian, Candidates 1971 (Game 2)
After 29...Bxb5 30. axb5, each side was left with a bishop of opposite color. Fischer converted only because both rooks remained and his bishop dominated the dark squares around Black’s king. [[Pgn|1. e4 c5 2. Nf3 d6 … 29...Bxb5 30. axb5
(full moves omitted)|fen|8/8/1p3k2/1P2p3/8/8/6P1/4B1K1 b - - 0 30]] -
Karpov – Kasparov, World Championship 1985, Game 16
A textbook defensive fortress: after exchanges, Kasparov’s dark-squared bishop and king blockaded Karpov’s passed pawns, and the game was drawn despite a nominal pawn deficit. -
Topalov – Shirov, Linares 1998
With queens and rooks on the board, both sides fired at opposite color complexes. Shirov sacrificed an exchange to expose g2 and finished with a spectacular mating attack, illustrating the sharp side of OCBs.
Historical Notes
• The defensive reputation of OCB endgames was firmly established in the
19th century. Wilhelm Steinitz, the first World Champion, routinely headed
for such endings to neutralize tactical wizards like Anderssen.
• Computer engines quantify the “drawishness” precisely: with equal pawns,
a side often needs to be two pawns up to expect a forced win.
• In the famous 1997 Kasparov vs. Deep Blue match (Game 2), the
machine sacrificed a pawn to obtain bishops of opposite color plus heavy
pieces—an early example of engine-driven strategy that out-prepared the
reigning champion.
Practical Tips
- When ahead with OCBs, avoid exchanges of heavy pieces. Keep queens or at least a pair of rooks.
- When behind, simplify. Every traded rook increases your drawing chances exponentially.
- Remember the rhyme: “Same bishops favor the flank; opposite bishops favor the bank.” (It hints that attacks flourish on the kingside while pawns melt away on the queenside!)
- In pure bishop endgames, try to place pawns on the color of your own bishop to maximize mobility, the opposite of the usual heuristic.
Interesting Anecdotes
• GM Miguel Najdorf once joked that “if you want a quick draw, trade a pair
of bishops; if you want a quick win, keep the queens.” Opposite bishops let
you choose.
• The phrase “the perpetual check factory” originated from analysis
of OCB middlegames where a queen and bishop repeatedly attack squares the
lone defending bishop can never cover, producing endless checks.
• In correspondence chess, players deliberately steer into OCB endings a
pawn down, trusting fortresses that human opponents might underestimate—but
engines usually defend them flawlessly today.