Quick answer
Checking from Behind is an endgame technique: Lucena bridge-building. Work from the first evidence position for Checking from Behind, and begin by testing Kc5.
Begin from Kc5 in 7k/2P5/2K5/8/8/8/7r/4R3 w - - 2 2. Count the material, king routes, promotion squares and reserve tempi before applying a theoretical rule. The evidence answer is: Checking from Behind: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kc5.
In the Checking from Behind example, notice: side White; pieces Black king h8, White pawn c7, White king c6, Black rook h2, White rook e1; legal first moves c8=N, c8=B, c8=R+, c8=Q+, Kb7, Kd7, Kd6, Kd5. 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. Where the evidence stores a move string, A is built with direct FEN setup and B with direct FEN setup. Related definitions sit in the Chess Wiki and the Endgames hub. Then compare Material Values with Rook Behind A Passed Pawn, Cut Off King In Rook Endings, Lucena Position around an outside passer used as a decoy.
The two inventories make the distinction concrete. A contains side White; pieces Black king h8, White pawn c7, White king c6, Black rook h2, White rook e1; legal first moves c8=N, c8=B, c8=R+, c8=Q+, Kb7, Kd7, Kd6, Kd5; B contains side Black; pieces White bishop c8, Black king h8, White king c6, Black rook h5, White rook a3; legal first moves Kh7, Kg7, Kg8, Rh6+, Rh7, Rh4, Rh3, Rh2. Compare the side to move before comparing the labels in the context of the defender's only active counterplay.
Topic dossier for this page and board pair r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:7r | r8:4R3 / r1:2B4k | r2:8 | r3:2K5 | r4:7r | r5:8 | r6:R7 | r7:8 | r8:8: start with an outside passer used as a decoy; then test the defender's only active counterplay; keep the pawn's promotion square separate from the defender's fortress setup; use the side-to-move tempo as the transfer check; and reserve a reserve pawn move for the exception.
Conversion or defense plan
On the first board, calculate Kc5 after Kc5 and write down the opponent's best reply around an outside passer used as a decoy. On the second board, calculate Kh7 after Kh7 and check the defender's only active counterplay. 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 a reserve pawn move.
Key claim: Checking from Behind is illustrated here by Lucena bridge-building; the first concrete test is Kc5. The board anchor is 7k/2P5/2K5/8/8/8/7r/4R3; 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 checking from behind, and how should each side play them?”, compare the recorded setup with Kh7 and the opponent's reply. The decision is useful only when the stated condition survives that concrete test on board 2B4k/8/2K5/7r/8/R7/8/8. The evidence records No tablebase outcome is asserted by this generated record; verify the exact FEN before publication and the second board signature r1:2B4k | r2:8 | r3:2K5 | r4:7r | r5:8 | r6:R7 | r7:8 | r8:8. The false-positive test is whether the pawn's promotion square appears without the defender's fortress setup, so the conclusion is useful only when the stated condition survives that concrete test.
Evidence positions
example-1: Lucena bridge-building
Show answer
Checking from Behind: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kc5.
Why this position is here: Checking from Behind is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 7k/2P5/2K5/8/8/8/7r/4R3; no opening history is inferred from the diagram.
FEN: 7k/2P5/2K5/8/8/8/7r/4R3 w - - 2 2
Question: What is the first concrete decision in this checking from behind position?
Answer cue: Checking from Behind: 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/2P5/2K5/8/8/8/7r/4R3 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
Checking from Behind: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kh7.
Why this position is here: Checking from Behind is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 2B4k/8/2K5/7r/8/R7/8/8; no opening history is inferred from the diagram.
FEN: 2B4k/8/2K5/7r/8/R7/8/8 b - - 0 2
Question: What is the first concrete decision in this checking from behind position?
Answer cue: Checking from Behind: 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 2B4k/8/2K5/7r/8/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-3: Lucena bridge-building
Show answer
Checking from Behind: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kh6.
Why this position is here: Checking from Behind is represented by Lucena bridge-building. This is a direct FEN setup with board anchor 1Q6/6kr/2K5/8/8/8/8/R7; no opening history is inferred from the diagram.
FEN: 1Q6/6kr/2K5/8/8/8/8/R7 b - - 2 2
Question: What is the first concrete decision in this checking from behind position?
Answer cue: Checking from Behind: use the king's shelter and a checking-distance bridge before advancing the pawn. Candidate line: Kh6. The first candidate to test is Kh6. Replay Kh6 on board anchor 1Q6/6kr/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.
Reading the line
Read the first example (id example-1) as a complete record: continuation Kc5, source tablebase. This is a direct FEN setup with board anchor 7k/2P5/2K5/8/8/8/7r/4R3; 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 Kh7, source tablebase. Its feature is Lucena bridge-building; inventory side Black; pieces White bishop c8, Black king h8, White king c6, Black rook h5, White rook a3; legal first moves Kh7, Kg7, Kg8, Rh6+, Rh7, Rh4, Rh3, Rh2. Compare what changes between Kc5 and Kh7.
Boundary cases
The main mistake to avoid with Checking from Behind 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 r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:7r | r8:4R3 after Kc5; in B, test it against r1:2B4k | r2:8 | r3:2K5 | r4:7r | r5:8 | r6:R7 | r7:8 | r8:8 after Kh7.
For Checking from Behind, the first board's evidence boundary (after Kc5) is No tablebase outcome is asserted by this generated record; verify the exact FEN before publication. The second board's evidence boundary for Checking from Behind 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 side-to-move tempo, 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 r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:7r | r8:4R3; record two candidates, the reply to Kc5 and the correction. Repeat with B's side to move and r1:2B4k | r2:8 | r3:2K5 | r4:7r | r5:8 | r6:R7 | r7:8 | r8:8; the changed board tests transfer rather than diagram memory.
After the drill, compare your notes with Rook Behind A Passed Pawn, Cut Off King In Rook Endings, Lucena Position through the defender's fortress setup. Keep A's rejected alternative beside B's chosen line Kh7; this shows whether the conclusion survived a new board signature.
Sources and scope
Sources for Checking from Behind: 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 r1:7k | r2:2P5 | r3:2K5 | r4:8 | r5:8 | r6:8 | r7:7r | r8:4R3 / r1:2B4k | r2:8 | r3:2K5 | r4:7r | r5:8 | r6:R7 | r7:8 | r8:8: this page does not claim that Kc5 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 pawn's promotion square.