Quick answer
Rook Behind a Passed Pawn is an endgame technique: Lucena bridge-building. Work from the first evidence position for Rook Behind a Passed Pawn, and begin by testing Ra8.
Begin from Ra8 in 2Q5/6kr/2K5/8/8/8/8/R7 w - - 1 2. Count the material, king routes, promotion squares and reserve tempi before applying a theoretical rule. The evidence answer is: Rook Behind a Passed Pawn: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8.
In the Rook Behind a Passed Pawn example, notice: side White; pieces White queen c8, Black king g7, Black rook h7, White king c6, White rook a1; legal first moves Qd8, Qe8, Qf8+, Qg8+, Qh8+, Qd7+, Qe6, Qf5. 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. A is seeded by the moves direct FEN setup. B is seeded by direct FEN setup. Definitions for adjacent ideas are on the Chess Wiki and the Endgames hub. Then compare Material Values with Rook Versus Pawn, Checking From Behind, Cut Off King In Rook Endings around the active rook before the pawn push.
The two inventories make the distinction concrete. A contains side White; pieces White queen c8, Black king g7, Black rook h7, White king c6, White rook a1; legal first moves Qd8, Qe8, Qf8+, Qg8+, Qh8+, Qd7+, Qe6, Qf5; B contains side Black; pieces White knight c8, Black king h8, Black rook a7, White rook a6, White king c5; legal first moves Kh7, Kg7, Kg8, Ra8, Rb7, Rc7+, Rd7, Re7. Compare the side to move before comparing the labels in the context of the conversion move order.
Topic dossier for this page and board pair r1:2Q5 | r2:6kr | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:8 | r8:R7 / r1:2N4k | r2:r7 | r3:R7 | r4:2K5 | r5:8 | r6:8 | r7:8 | r8:8: start with the active rook before the pawn push; then test the conversion move order; keep the side-to-move tempo separate from a reserve pawn move; use the pawn's promotion square as the transfer check; and reserve the defender's fortress setup 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 active rook before the pawn push. On the second board, calculate Ra8 after Ra8 and check the conversion move order. 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 fortress setup.
Key claim: Rook Behind a Passed Pawn is illustrated here by Lucena bridge-building; the first concrete test is Ra8. The board anchor is 2Q5/6kr/2K5/8/8/8/8/R7; 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 behind a passed pawn, 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 2N4k/r7/R7/2K5/8/8/8/8. The evidence records No tablebase outcome is asserted by this generated record; verify the exact FEN before publication and the second board signature r1:2N4k | r2:r7 | r3:R7 | r4:2K5 | r5:8 | r6:8 | r7:8 | r8:8. The false-positive test is whether the side-to-move tempo appears without a reserve pawn move, so the conclusion is useful only when the stated condition survives that concrete test.
Evidence positions
example-1: Lucena bridge-building
Show answer
Rook Behind a Passed Pawn: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8.
Why this position is here: Rook Behind a Passed Pawn is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 2Q5/6kr/2K5/8/8/8/8/R7; no opening history is inferred from the diagram.
FEN: 2Q5/6kr/2K5/8/8/8/8/R7 w - - 1 2
Question: What is the first concrete decision in this rook behind a passed pawn position?
Answer cue: Rook Behind a Passed Pawn: 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 2Q5/6kr/2K5/8/8/8/8/R7 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 Behind a Passed Pawn: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Ra8.
Why this position is here: Rook Behind a Passed Pawn is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 2N4k/r7/R7/2K5/8/8/8/8; no opening history is inferred from the diagram.
FEN: 2N4k/r7/R7/2K5/8/8/8/8 b - - 4 3
Question: What is the first concrete decision in this rook behind a passed pawn position?
Answer cue: Rook Behind a Passed Pawn: 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 2N4k/r7/R7/2K5/8/8/8/8 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 Behind a Passed Pawn: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kc5.
Why this position is here: Rook Behind a Passed Pawn is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 7k/2P5/4R3/3K4/5r2/8/8/8; no opening history is inferred from the diagram.
FEN: 7k/2P5/4R3/3K4/5r2/8/8/8 w - - 6 4
Question: What is the first concrete decision in this rook behind a passed pawn position?
Answer cue: Rook Behind a Passed Pawn: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kc5. The first candidate to test is Kc5. Replay Kc5 on board anchor 7k/2P5/4R3/3K4/5r2/8/8/8 and write down what changes after it.
Evidence boundary: No tablebase outcome is asserted by this generated record; verify the exact FEN before publication.
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 2Q5/6kr/2K5/8/8/8/8/R7; 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 Black; pieces White knight c8, Black king h8, Black rook a7, White rook a6, White king c5; legal first moves Kh7, Kg7, Kg8, Ra8, Rb7, Rc7+, Rd7, Re7. Compare what changes between Ra8 and Ra8.
Boundary cases
The main mistake to avoid with Rook Behind a Passed Pawn 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 r1:2Q5 | r2:6kr | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:8 | r8:R7 after Ra8; in B, test it against r1:2N4k | r2:r7 | r3:R7 | r4:2K5 | r5:8 | r6:8 | r7:8 | r8:8 after Ra8.
For Rook Behind a Passed Pawn, 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 Behind a Passed Pawn 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 the pawn's promotion square, 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 r1:2Q5 | r2:6kr | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:8 | r8:R7; record two candidates, the reply to Ra8 and the correction. Repeat with B's side to move and r1:2N4k | r2:r7 | r3:R7 | r4:2K5 | 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 Pawn, Checking From Behind, Cut Off King In Rook Endings through a reserve pawn move. 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 Behind a Passed Pawn: 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 r1:2Q5 | r2:6kr | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:8 | r8:R7 / r1:2N4k | r2:r7 | r3:R7 | r4:2K5 | 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 side-to-move tempo.