A zwischenzug, or in-between move, is a surprise move (often a check or a stronger threat) inserted before the reply your opponent is expecting.
When a piece is captured or attacked, both players assume the ‘natural’ reply will come next — usually a recapture or retreat. A zwischenzug breaks that assumption by squeezing in an even more forcing move first.
Because the in-between move makes a threat the opponent must answer, you get to deal with the original situation a move later — but now on better terms, often a tempo or a whole piece to the good. The trick is realising you don’t have to recapture immediately.
Missing the opponent’s zwischenzug is a classic way to lose material: you assume a trade is forced, recapture automatically, and walk into a stronger in-between shot. Always check for forcing moves before you ‘obviously’ recapture.
Roughly ‘TSVISH-en-tsook’ — it’s German for ‘in-between move’. It’s also called an intermezzo.
Right before any ‘automatic’ recapture or retreat. Ask whether you have a check or a bigger threat to insert first — answering that one move later often wins material or a tempo.
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