Rook vs Bishop
Rook against bishop with no pawns is a theoretical draw — but only for a defender who knows where to stand. The whole ending compresses into one rule: run your king to the corner that is not your bishop's color. In the safe corner the defense is a fortress no rook can crack; in the bishop-colored corner the same material loses to a forced mate in a handful of moves. Few endings punish a single wrong turn this brutally.
Why the Rook Cannot Win — Until the Edge
In the middle of the board, rook versus bishop is a comfortable draw. The rook cannot deliver mate without its king, the bishop is a nimble piece that is hard to trap in open space, and there is no zugzwang to speak of — the bishop always has a spare move along a long diagonal. The defender simply keeps the king reasonably central, keeps the bishop out of the rook's reach, and shuffles.
The danger begins when the attacking king arrives and starts herding the defending king toward the edge. The defender cannot avoid this forever — king and rook together always drive a lone king back, just as in the basic rook mate. So the real question of the ending is not whether your king will be pushed to the edge, but where you choose to be pushed. That choice — which corner you retreat toward — is the entire theory of rook versus bishop, and it is decided by the color of your bishop.
The Safe Corner Fortress
The rule: the defending king belongs in the corner opposite the bishop's color. A light-squared bishop defends from the dark corners (h8 or a1 in the diagram's geometry); a dark-squared bishop from the light corners. Here is the fortress at its moment of truth. White: king g6, rook a7. Black: king h8, bishop d5 — a light-squared bishop in the dark corner, the right address. White has achieved everything possible — king at point-blank range, rook poised — and there is no way in.
1...Bg2 — the bishop simply waits on the long diagonal, staying far from the rook. Note it must keep its distance: a bishop that drifts within the rook's reach can be attacked and dominated, so the far end of the diagonal is home. 2.Re7 Bd5 3.Re8+ looks like the beginning of the end — a back-rank check against a king with no flight squares. But 3...Bg8! is the move the whole fortress is built on. The bishop blocks the check on g8, right beside its king, defended by it.
Now count White's options and watch each one die. Capturing, 4.Rxg8+ Kxg8, leaves rook-less White with a drawn king ending — insufficient material. Keeping the pin by sliding along the eighth rank, say 4.Rd8, produces stalemate on the spot: the pinned bishop cannot legally move, and the king on h8 has no squares because White's own king covers g7 and h7. And any move that releases the pin — 4.Re7, or a king move off g6 — lets the bishop float back out to d5 and the dance restarts. Every road leads to a draw, which is exactly what the tablebase confirms from the diagram: with the light-squared bishop and the dark corner, White cannot make progress from the most favorable setup imaginable.
The geometric heart of the fortress is worth stating plainly, because it explains the wrong corner too: the interposition square next to the king — g8 — is a light square, so the light-squared bishop can stand there, and the king can defend it. Color is everything.
The Wrong Corner: Collapse in Two Moves
Now repaint the bishop. Same kings, same rook — White: king g6, rook a7; Black: king h8 — but give Black a dark-squared bishop on d2. The king now sits in the corner of its own bishop's color, and the position is lost by force. The tablebase gives mate in two moves against any defense.
1...Bb4, hurrying to cover f8 — the only try. 2.Ra8+ Bf8 and the bishop does interpose, but look where: f8, two squares from the king, where only the bishop itself occupies the checking line. 3.Rxf8#. The rook captures, the check reopens along the eighth rank through the empty g8, and the king on h8 has nothing — g7 and h7 belong to White's king, g8 to the rook.
Compare this with the fortress diagram and the color logic snaps into focus. The blocking square the king could actually defend — g8 — is a light square, forever out of the dark-squared bishop's reach. So the bishop is condemned to block far from home on b8, d8 or f8, and a block the king does not defend is just a delayed capture. Same material, same corner, opposite bishop color: mate instead of fortress. When I show students both diagrams side by side, nobody ever forgets the rule again.
Playing the Defense — and Playing for the Win
As the defender, start planning your corner early, while your king is still being herded. Head for the corner your bishop does not own, even if it is the longer walk — a tempo spent now is worth half a point later. Keep the bishop on a long diagonal far from the enemy rook, so it cannot be attacked and driven with gain of time; the bishop's nightmare is being forced to squares where the rook wins it with a skewer or traps it against the edge. And once you reach the fortress, do nothing: shuffle the bishop along its diagonal and let the attacker exhaust ideas. Note the defense also enjoys a hard deadline — with no pawn moves or captures available, the attacker is racing the fifty-move clock.
As the attacker, your only real winning chances are on the way to the fortress. Herd the defending king toward the corner of the bishop's color — cut it off along ranks and files and give it no choice of exits. Harass the bishop with the rook to steal tempi; a defender forced to choose between king route and bishop safety often chooses wrong. If the defender reads the position correctly and reaches the safe corner, take the draw gracefully — there is genuinely nothing there, and flailing risks nothing except your dignity. The same herding logic, incidentally, is far more profitable against a knight, which cannot match the bishop's long-range shuffling — see rook vs knight.
Rook vs Bishop With Pawns on the Board
Add pawns and the evaluation changes completely: being up the exchange is normally a serious, often decisive advantage. The rook outclasses the bishop at every pawn-ending job — it attacks pawns from front and side, ties the enemy king to defense, and escorts its own passer while the bishop can only watch squares of one color. With pawns on both wings, the rook side's standard plan is to attack pawns fixed on squares the bishop cannot defend, create a passer on the wing the bishop serves badly, and trade down toward a winning basic ending.
The bishop side's drawing chances rest on two pillars. The first is the fortress idea writ large: a compact pawn chain on the bishop's color, king in front, no entry squares for the enemy king or rook — many exchange-down positions hold exactly this way, which is why the positional exchange sacrifice is playable at all. The second is reduction: every pawn trade moves the position closer to the pawnless draw of this article. As the rook side, keep pawns on the board and keep play on both wings; as the bishop side, trade pawns at every honest opportunity and build your structure on your bishop's color. And if all the pawns do come off, you already know the final chapter — sprint your king toward the right corner.
Frequently Asked Questions
Is rook vs bishop a draw?
Yes, with no pawns it is a theoretical draw, but the defense has to be exact once the king is driven to the edge. The defending king must reach the corner opposite the bishop's color; in the bishop-colored corner the position is lost to a short forced mate.
What is the safe corner in rook vs bishop?
The corner that is not the bishop's color: dark corners for a light-squared bishop, light corners for a dark-squared bishop. There the bishop can block a back-rank check on the square directly beside the king, defended by it, and the attacker gets nothing better than stalemate tricks.
Why does the wrong corner lose?
Because the blocking square next to the king is the wrong color for the bishop, so the bishop must interpose far from the king on an undefended square. The rook simply captures the blocker and delivers mate along the back rank, often within two or three moves.
Can the rook ever trap the bishop?
Yes — that is the attacker's main practical chance on the way to the corner. A bishop that strays close to the rook or gets stuck near the edge can be dominated and won, converting to a basic rook mate. Defenders should park the bishop far away on a long diagonal and move it as little as possible.
Is being up the exchange winning with pawns on the board?
Usually, yes — rook versus bishop with pawns favors the rook strongly, and most such endings are won with patient play on both wings. The bishop side draws mainly through fortress setups on its own color or by trading all the pawns to reach the pawnless draw.