Editing Interference (chess) (section)

==Examples==
{{Chess diagram
|tleft
|Diagram A
|  |  |kd|rd|  |bd|  |  
|pd|pd|pd|  |  |  |  |pd
|  |  |  |  |  |  |pd|  
|  |  |  |  |pl|nl|  |  
|  |  |  |  |  |  |  |  
|  |  |  |  |  |  |  |pl
|pl|  |  |qd|ql|pl|pl|  
|  |  |  |  |rl|  |kl|  
|White to move
}}
In diagram A, White to play will apparently be obliged to retreat the knight from f5, because the squares to which it could advance are all guarded. The interference move 1.Nd6+, however, interrupts the black rook's defense of the black queen. If Black plays either 1...cxd6 or 1...Bxd6, White will capture Black's queen. Therefore, Black has no better play than 1...Rxd6 2.exd6 Qxe2 3.Rxe2 Bxd6, conceding [[the exchange (chess)|the exchange]] for a pawn.

A more subtle example of interference occurs when the interposing piece interrupts two lines simultaneously. In this case, the moving piece does not have to pose a threat by itself.  Instead, it makes the opponent "trip over their own feet" because capturing the offending piece will necessarily break one line of defense or the other.

{{Chess diagram
|tright
|Diagram B
|  |rl|  |rd|  |  |  |  
|pl|  |  |  |  |pd|  |kd
|  |  |  |  |  |  |pd|pd
|  |  |  |  |  |nd|  |  
|  |nl|  |  |bd|  |  |  
|kl|pl|  |  |  |  |  |  
|  |bl|pl|rd|  |  |  |pl
|  |  |  |  |  |  |  |  
|White to move
}}
In diagram B, White is at a {{chessgloss|material}} disadvantage, and apparently can't queen the a-pawn because the black bishop guards the queening square. However, 1.Nd5{{chesspunc|!}} interferes with the bishop and with the black rooks' defense of each other. If 1...Bxd5, 2.Rxd8 is crushing. If 1...R8xd5, then 2.Rh8 [[Checkmate|mate]]. The best Black can do is 1...R2xd5, interfering with the bishop's guard of a8 and permitting 2.a8=Q.

Although interferences are quite rare in actual play, they are a common theme in [[chess problem]]s. The device in the last example above, in which a sacrifice occurs on the intersection of the defensive lines of two differently moving pieces, is known to problemists as a ''[[Novotny (chess)|Novotny]]''. Various other types of interference are given specific names in [[Glossary of chess problems|problem terminology]], including the [[Grimshaw (chess)|Grimshaw]], [[Plachutta]] (where the two pieces both move orthogonally; see a [[Siegbert Tarrasch#Famous Tarrasch combinations|beautiful example by Tarrasch]]), [[anti-Bristol]], [[Holzhausen interference|Holzhausen]] and [[Wurzburg–Plachutta]].