FinalesJouer avec les white

Rook vs Bishop

Learn when K+R vs K+B is winning and how to exploit a trapped bishop on the edge of the board.

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Introduction

King and Rook vs King and Bishop is usually a draw — the bishop's long range lets it shuttle freely along diagonals, and the rook can never trap it. But there is one critical exception: when the bishop is stuck on the edge with its king unable to help, the rook can win it by force. In this lesson, Black's bishop is stranded on h7 while the king sits on b8 — too far away to defend it. White uses a series of rook checks to drive the Black king even further from the bishop, then captures it. After that, it's a straightforward King and Rook vs King checkmate. Recognizing when the bishop is trapped — and when it's safe — is the key skill in this endgame.

Contenu de la leçon

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1. Re8+

The rook seizes the 8th rank with check, driving the Black king away from the bishop on h7. This is the critical first step: the further the king gets from the bishop, the harder it is to defend it. From e8, the rook controls the entire back rank and prepares to swing to the 7th rank next.

Couper le roiTour active
Coups alternatifs
Rh1 — Moves toward the bishop but gives Black time to bring the king closer with Kc7, reaching a draw.
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1. ..Ka7

The king retreats to a7, moving further from the bishop on h7. Black cannot go to c7 because White's king on d6 controls that square. The bishop is now seven squares away from its king — far too distant for protection.

Couper le roi
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2. Re7+

The rook drops to the 7th rank with check! This is a double-purpose move: it forces the Black king to move again while simultaneously threatening Rxh7 on the next turn. The rook now controls the entire 7th rank, cutting off the bishop's only escape route (the h7-a diagonal crosses through the 7th rank).

Tour activeCouper le roiMenace
Coups alternatifs
Rxh7 — Not available — the rook is on e8, not e7. But even after Re7+, the bishop will be captured next move. It's more precise to check first.
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2. ..Kb6

Black steps to b6, the best defense — staying as close to the center as possible. But the bishop on h7 is still undefended and the rook on e7 can capture it immediately. The king is simply too far away to help.

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3. Rxh7

The rook captures the trapped bishop! This is the payoff of the checking sequence: two checks drove the king to b6, leaving the bishop on h7 completely undefended. The position is now King and Rook vs lone King — a basic theoretical win. This moment illustrates the key lesson: in K+R vs K+B, the bishop is only vulnerable when it's on the edge and its king can't reach it in time. If Black's king had been on g8 instead of b8, the bishop would have been defended and the position drawn.

Tour activeGain par tablebases
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3. ..Kb5

With the bishop gone, Black's king heads toward the center — the best defensive strategy in K+R vs K. A centralized king is harder to push to the edge. White must now use the classic box technique: restrict the king's area with the rook, then bring the king closer to assist.

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4. Rh4

The rook cuts off the king along the 4th rank. Black's king cannot cross below the 4th rank, confining it to the top half of the board. This is the box technique in action — the rook creates a wall that shrinks the king's territory.

Couper le roiTour active
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4. ..Kb6

Black moves back to b6, staying within the confined area. The king can't cross the 4th rank because the rook controls it. White's next step: push the king toward the edge with a check.

Couper le roi
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5. Rb4+

Check on the b-file! The rook shifts from the 4th rank to the b-file, giving check and tightening the box — the king is now confined to the a-file. This is a key pattern: the rook alternates between cutting off ranks and files to push the king toward the corner.

Couper le roiTour active
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5. ..Ka5

Forced to the a-file. The king is now confined to the a-file and upper half of the board — a very small box. White's king must advance to support the rook in delivering the final checkmate.

Couper le roi
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6. Kc5

The king marches forward. White's king heads toward the action — it needs to be close to the Black king to help deliver checkmate. The rook holds the barrier on the b-file while the king approaches. In K+R vs K, both pieces must cooperate: the rook restricts, the king assists.

Activité des piècesCouper le roi
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6. ..Ka6

Black's only legal move. The king can't cross the b-file (rook controls it), and Kc6 is controlled by White's king. The box is almost sealed.

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7. Kc6

The king gains opposition on the 6th rank. From c6, the king controls b7 and c7, which prevents the Black king from escaping toward the center. Together with the rook on b4, every escape route is blocked. White is now ready to deliver the final checks.

OppositionCouper le roi
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7. ..Ka7

The king retreats to a7 — forced along the edge. Kb7 is controlled by White's king on c6, and the a-file remains the only option. Black is running out of squares.

Couper le roi
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8. Ra4+

Check from the 4th rank! The rook swings to a4, giving check and driving the king to the 8th rank — the last rank. After this check, Black has only one legal square: b8. The back rank is the final destination.

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8. ..Kb8

Forced to b8 — the back rank. Ka8 is controlled by the rook on the a-file, and Kb6 and Kb7 are controlled by White's king. The king is cornered.

Couper le roi
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9. Ra1

A quiet waiting move — the most important move of the mating sequence! The rook retreats to a1, sealing the a-file. Now the Black king cannot go to a8 or a7 (a-file controlled by rook), and cannot go to b7 or c7 (controlled by White's king on c6). The only legal move is Kc8, walking into opposition with White's king.

ZugzwangCouper le roi
Coups alternatifs
Ra8+ — Draws! The Black king captures the rook with Kxa8 — it's adjacent to a8. Always be careful not to put the rook where the king can capture it.
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9. ..Kc8

Forced — the only legal move. The king walks into perfect opposition with White's king on c6. This is exactly what White wanted: the two kings face each other on the same file with one square between them, and the rook delivers the finishing blow.

OppositionZugzwang
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10. Ra8#

Checkmate! The rook delivers mate from a8, controlling the entire 8th rank. The Black king on c8 has no escape: b8 and d8 are covered by the rook, while b7, c7, and d7 are covered by White's king. A clean finish to an endgame that combined bishop trapping with rook mating technique.

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Points clés

  • K+R vs K+B is normally a draw — the bishop has too much range to be trapped
  • The exception: when the bishop is on the edge and its king is too far away to defend it
  • Use rook checks to drive the defending king further from the bishop before capturing it
  • After winning the bishop, apply the box technique: cut off the king with the rook, advance your own king, and mate on the back rank
  • Never put your rook on a square adjacent to the enemy king — it can be captured!

Résumé

You've learned the rare winning case of King and Rook vs King and Bishop. When the bishop is stranded on the edge far from its king, a series of rook checks drives the king away, leaving the bishop undefended. After capturing it, the standard K+R vs K mating technique finishes the job: restrict the king with the rook, advance your king, and deliver back-rank checkmate.

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