This particular Chess Tactic, known either as Intermezzo (popular in America) or Zwischenzug (more common in Europe), aims to deceive your opponent with a surprise move made in the build up to your main line of attack.
The literal translation of both terms is “in-between move” or “intermediate move”, as that’s precisely what happens, you make an intermediate move prior to your main move.
Intermezzo Chess Tactic
Three examples of the Intermezzo / Zwischenzug / In-between Move tactic being used …
1) Example 1
The expected move: Black’s d5-Pawn (red square) to capture White’s Be4.
The Intermezzo: Black’s Qd8 (yellow square) to h4 (green square).
The purpose: Black’s Qh4, pins White’s f-Pawn, preventing it from advancing, while Be4 can’t move because of Qh4xf2#.
2) Example 2
The expected move: Black’s Qb6 (red square) to capture White’s Bc4, also checking White’s Ke1.
The Intermezzo: Rc8 (yellow square) to Rc1+ (green square).
The purpose: Exchange Rooks … before capturing White’s Bb4 (with Qb6xb4).
3) Example 3
The expected move: Black’s Ra8 (red square) to capture White’s dark-Bishop on b8.
The Intermezzo: Nf6 (yellow square) to d5 (green square).
The purpose: Move the Knight to a more-advanced square … before capturing White’s dark-Bishop (with …Rxb8).