Interference

Interference is a tactic where you drop a piece in between two enemy pieces that are working together, cutting the line that connects them. When one piece guards another piece - or an important square - along an open line (a file, rank, or diagonal), putting a piece on that line makes the defense stop working. The guard is cut, and whatever threat it was holding back can now be carried out.

Why Interference Works

Rooks, bishops, and queens reach far along open lines. That reach only holds while nothing sits in between. If an enemy piece is guarding a distant square, simply placing a piece on the line between them cuts the defense. The guarding piece is still on the board, but with its view blocked it can no longer do its job. Interference switches off a piece's function without capturing it.

Here is a position from this site's puzzles (White to move). Two black rooks are stacked on the open d-file.

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White wants to take the d8-rook with the queen and mate the king. But right now the d1-rook guards d8 down the same open file, so grabbing it straight away is met by Rxd8. So White cuts between the two rooks before capturing. The first move is Bd3+.

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That single move does two things at once. Opening the h-file checks the king and forces Kg8, and the bishop planted on d3 blocks the d-file, cutting the link between the d1-rook and the d8-rook. Because Black had to answer the check, there was no time to remove the bishop, and the d8-rook is no longer protected from behind. With the king now on g8, capturing that rook also gives check along the back rank: Qxd8#.

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Bd3+ Kg8 Qxd8#. The very move that takes the rook is checkmate. Had there been no bishop on d3, the d1-rook would answer Rxd8 and nothing would have happened. Because a single bishop stood on the d-file and cut that defensive link, there was no piece left to recapture the queen. The interfering move itself captured nothing - a piece simply stepped in between two enemy pieces and severed their connection. That is the whole idea of interference.

How to Spot Interference

A useful order when you hunt for interference: first, ask why the decisive move you want (a capture or a mate) does not work right now. Usually it is because an enemy piece guards the square along an open line. Then look for an empty square on that guarding line, in between, where you can drop a piece. Put a piece there and the defense is cut. Better still if the move there also gives a check or another threat, because then the opponent has no time to capture the intruder or deal with it.

Interference by Our Numbers

This site's puzzle DB tags 1,010 puzzles as interference (measured July 2026). That is less than a tenth of the advanced-pawn tag (14,144), so it is a relatively rare motif.

The number that stands out is the rating spread. 37% of interference puzzles are rated 2000 or above, and only 9% are below 1200. For comparison, 23.8% of fork puzzles sit below 1200; interference leans toward the higher end. It suggests that noticing the unseen link between two pieces and stepping in between is a pattern players tend to pick up relatively late.

Interference also often comes with other tactics: of the interference puzzles, 11.9% also carry the deflection tag, 10.0% fork and 5.3% discovered attack. The example above was in fact both an interference and a discovered check. A line-cutting move is at its strongest when it also delivers a check or another threat.

For the Defender

• Watch the square where a link could be cut. If two of your pieces guard each other, or an important square, along a single open line, the empty square between them is a weak spot. Check whether the opponent can put a piece there.
• Do not lean on a single line for defense. If an important square is held by two or more pieces from different directions, blocking one line still leaves the defense standing.
• Capture or chase the intruder. If you can take the piece dropped in between, the link comes back to life. But if that piece also gives check, you have to answer the check first and may get no time to take it.

References

• Lichess, puzzle theme Interference (the source of this site's puzzle tags). https://lichess.org/training/themes
• Example position: Lichess puzzle 5Ln1a (CC0). https://lichess.org/training/5Ln1a
• Statistics: scripts/analyze-interference-stats.mjs, results recorded in docs/data/interference-stats.md.

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Start training: Interference training

Related: Deflection · Discovered attack · All tactics