Interference (chess) Interference (chess) In the game of chess, interference occurs when the line between an attacked piece and its defender is interrupted by sacrificially interposing a piece. It is a chess tactic which seldom arises, and is therefore often overlooked. Opportunities for interference are rare because the defended object must be more valuable than the sacrificed piece, and the interposition must itself represent a threat. In the position at left, White to play will apparently be obliged to retreat the knight from f5, because the squares to which it could advance are all guarded. However, the interference move 1.Nd6+ interrupts the
History of chess a disadvantage, as the other player would have a long period to analyze before having to make a reply when the game was resumed. Preventing access to a chess set to work out moves during the adjournment would not stop him from analyzing the position in his head. Various strange ideas were attempted, but the eventual solution was the "sealed move". The final move before adjournment is not made on the board but instead is written on a piece of paper which the referee seals in an envelope and keeps safe. When the game is continued after adjournment, the referee