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
Empress (chess) attacking archbishop two squares diagonally away), while the rook+knight compound cannot. Worse, the word empress suggests a piece stronger than the queen, while this piece is at best equal to and perhaps weaker than the queen, especially in the endgame. The empress was first used in Turkish Great Chess, a large medieval variant of chess, where it was called the "war machine" (dabbabah; not to be confused with the piece more commonly referred to as the dabbaba today, which is the (2,0) leaper). It was introduced in the West with Carrera's chess from 1617, where it was called a "champion",