Interference — what it means in chess
Interposing a piece to cut the line between an enemy piece and what it defends.
Interposing a piece to cut the line between an enemy piece and what it defends.
Interference plants a piece on the line between an enemy defender and the thing it defends. The guard is not captured, chased, or overworked — its line of sight is cut. And the finest versions have a built-in cruelty: capturing the interfering piece puts the capturer on the same square, so the line stays cut.
[[board startfen="6k1/1p3ppp/8/3PN3/q7/8/8/4R1K1 w - - 0 1" pgn="1. Nc6 bxc6 2. Re8 " caption="Interference: the knight lands on the guard line, and even the recapture keeps it blocked." notes="White to move. The Black queen on a4 guards e8 along the long diagonal — the only thing stopping Re8 mate. Nc6 — the knight lands on the diagonal, cutting the queen's view of e8. Taking with the queen loses her to the d5 pawn; the pawn capture is the main try. bxc6 — but the recapturing pawn lands on c6, the exact square that was doing the blocking. The line is still cut. Re8 — the back-rank mate the queen could no longer see."]]
The mate that lands here is a back-rank mate; the family it belongs to is the guard-fighting trio of deflection, removing the defender, and overloading — interference is the fourth way to beat a defender: leave it alone and blind it.
The Endgame Society glossary defines more than 240 chess terms — rules, notation, tactics, strategy, pawn structures, endgames, and openings — in language a beginner can act on rather than dictionary shorthand.