Colle System Puzzle (Rated 1446): Refute — Knight Fork
A knight fork can look powerful when it attacks a queen and another valuable target, but the position must be checked for forcing replies. The key defensive idea is to answer the fork with an even stronger tactical resource, especially when the attacking knight has moved away from defending a queen or vulnerable piece. In this middlegame, Black exploits the alignment of the pieces and turns White’s apparent initiative into a decisive material gain.