Quick answer
Rook and Bishop versus Rook is an endgame technique: Lucena bridge-building. Work from the first evidence position for Rook and Bishop versus Rook, and begin by testing Ra8.
Begin from Ra8 in 8/2P3k1/8/3K4/7r/R7/8/8 w - - 4 3. Count the material, king routes, promotion squares and reserve tempi before applying a theoretical rule. The evidence answer is: Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8.
In the Rook and Bishop versus Rook example, notice: side White; pieces White pawn c7, Black king g7, White king d5, Black rook h4, White rook a3; legal first moves c8=N, c8=B, c8=R, c8=Q, Kc6, Kd6, Ke6, Ke5. Use the inventory as a reading aid for this position alone rather than as a template for other games.
Material and result question
The first evidence board tests Lucena bridge-building; the second board tests Lucena bridge-building. Use direct FEN setup to reconstruct A and direct FEN setup to reconstruct B when the evidence includes move text. Related definitions sit in the Chess Wiki and the Endgames hub. Then compare Material Values with Rook Versus Minor Piece, Two Rooks Versus Rook, Minor Piece And Pawn Versus Rook around the side-to-move tempo.
The two inventories make the distinction concrete. A contains side White; pieces White pawn c7, Black king g7, White king d5, Black rook h4, White rook a3; legal first moves c8=N, c8=B, c8=R, c8=Q, Kc6, Kd6, Ke6, Ke5; B contains side White; pieces White rook h8, White pawn c7, Black king g7, White king c6, Black rook h5; legal first moves Rh7+, Rh6, Rxh5, Rg8+, Rf8, Re8, Rd8, Rc8. Compare the side to move before comparing the labels in the context of a reserve pawn move.
Topic dossier for this page and board pair r1:8 | r2:2P3k1 | r3:8 | r4:3K4 | r5:7r | r6:R7 | r7:8 | r8:8 / r1:7R | r2:2P3k1 | r3:2K5 | r4:7r | r5:8 | r6:8 | r7:8 | r8:8: start with the side-to-move tempo; then test a reserve pawn move; keep the active rook before the pawn push separate from the conversion move order; use an outside passer used as a decoy as the transfer check; and reserve the defender's only active counterplay for the exception.
Conversion or defense plan
On the first board, calculate Ra8 after Ra8 and write down the opponent's best reply around the side-to-move tempo. On the second board, calculate Ra8 after Ra8 and check a reserve pawn move. Separate the practical conversion question from the result question; side to move and one checking distance can change the conclusion. In this case the useful condition is the defender's only active counterplay.
Key claim: Rook and Bishop versus Rook is illustrated here by Lucena bridge-building; the first concrete test is Ra8. The board anchor is 8/2P3k1/8/3K4/7r/R7/8/8; the example is intentionally narrower than the topic label and should not be generalised without checking the surrounding position..
Practical boundary: To answer “What exact king, pawn, and move-order conditions decide rook and bishop versus rook, and how should each side play them?”, compare the recorded setup with Ra8 and the opponent's reply. The decision is useful only when the stated condition survives that concrete test on board 7R/2P3k1/2K5/7r/8/8/8/8. The evidence records No tablebase outcome is asserted by this generated record; verify the exact FEN before publication and the second board signature r1:7R | r2:2P3k1 | r3:2K5 | r4:7r | r5:8 | r6:8 | r7:8 | r8:8. The false-positive test is whether the active rook before the pawn push appears without the conversion move order, so the conclusion is useful only when the stated condition survives that concrete test.
Evidence positions
example-1: Lucena bridge-building
Show answer
Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8.
Why this position is here: Rook and Bishop versus Rook is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 8/2P3k1/8/3K4/7r/R7/8/8; no opening history is inferred from the diagram.
FEN: 8/2P3k1/8/3K4/7r/R7/8/8 w - - 4 3
Question: What is the first concrete decision in this rook and bishop versus rook position?
Answer cue: Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8. The first candidate to test is Ra8. Replay Ra8 on board anchor 8/2P3k1/8/3K4/7r/R7/8/8 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
example-2: Lucena bridge-building
Show answer
Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8.
Why this position is here: Rook and Bishop versus Rook is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 7R/2P3k1/2K5/7r/8/8/8/8; no opening history is inferred from the diagram.
FEN: 7R/2P3k1/2K5/7r/8/8/8/8 w - - 6 4
Question: What is the first concrete decision in this rook and bishop versus rook position?
Answer cue: Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8. The first candidate to test is Ra8. Replay Ra8 on board anchor 7R/2P3k1/2K5/7r/8/8/8/8 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
example-3: Lucena bridge-building
Show answer
Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kh7.
Why this position is here: Rook and Bishop versus Rook is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 7k/2P5/8/3K4/8/8/7r/6R1; no opening history is inferred from the diagram.
FEN: 7k/2P5/8/3K4/8/8/7r/6R1 b - - 3 2
Question: What is the first concrete decision in this rook and bishop versus rook position?
Answer cue: Rook and Bishop versus Rook: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kh7. The first candidate to test is Kh7. Replay Kh7 on board anchor 7k/2P5/8/3K4/8/8/7r/6R1 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
Reading the line
Read the first example (id example-1) as a complete record: continuation Ra8, source tablebase. This is a direct FEN setup with board anchor 8/2P3k1/8/3K4/7r/R7/8/8; no opening history is inferred from the diagram. If A does not expose Lucena bridge-building, correct the evidence before relying on the prose.
Read the second example (id example-2) separately: continuation Ra8, source tablebase. Its feature is Lucena bridge-building; inventory side White; pieces White rook h8, White pawn c7, Black king g7, White king c6, Black rook h5; legal first moves Rh7+, Rh6, Rxh5, Rg8+, Rf8, Re8, Rd8, Rc8. Compare what changes between Ra8 and Ra8.
Boundary cases
The main mistake to avoid with Rook and Bishop versus Rook is applying a remembered endgame rule while ignoring side to move, king placement or an unverified result. In A, the missing condition must be located in r1:8 | r2:2P3k1 | r3:8 | r4:3K4 | r5:7r | r6:R7 | r7:8 | r8:8 after Ra8; in B, test it against r1:7R | r2:2P3k1 | r3:2K5 | r4:7r | r5:8 | r6:8 | r7:8 | r8:8 after Ra8.
For Rook and Bishop versus Rook, the first board's evidence boundary (after Ra8) is No tablebase outcome is asserted by this generated record; verify the exact FEN before publication. The second board's evidence boundary for Rook and Bishop versus Rook is No tablebase outcome is asserted by this generated record; verify the exact FEN before publication. If a trusted source or careful calculation changes the conclusion around an outside passer used as a decoy, update both the evidence record and this article.
Practice from a real game
play the position for both sides, record the critical tempo, and verify the exact FEN against the cited tablebase before publication. Start with A's side to move and r1:8 | r2:2P3k1 | r3:8 | r4:3K4 | r5:7r | r6:R7 | r7:8 | r8:8; record two candidates, the reply to Ra8 and the correction. Repeat with B's side to move and r1:7R | r2:2P3k1 | r3:2K5 | r4:7r | r5:8 | r6:8 | r7:8 | r8:8; the changed board tests transfer rather than diagram memory.
After the drill, compare your notes with Rook Versus Minor Piece, Two Rooks Versus Rook, Minor Piece And Pawn Versus Rook through the conversion move order. Keep A's rejected alternative beside B's chosen line Ra8; this shows whether the conclusion survived a new board signature.
Sources and scope
Sources for Rook and Bishop versus Rook: Syzygy tablebase verification reference, 1chess.online editorial scope. Source ids are tablebase, original-analysis. Primary evidence hook: tablebase. Comparisons and practice notes are editorial. Evidence revision: 2026-08-remediation-r2.
Scope note for board pair r1:8 | r2:2P3k1 | r3:8 | r4:3K4 | r5:7r | r6:R7 | r7:8 | r8:8 / r1:7R | r2:2P3k1 | r3:2K5 | r4:7r | r5:8 | r6:8 | r7:8 | r8:8: this page does not claim that Ra8 is an engine principal variation, that an exact endgame result is verified when the evidence says it is not, or that a tool output replaces human calculation. The conclusion is limited to the recorded boundary and the exception the active rook before the pawn push.