Knight fork
A knight fork is a move that places a knight on a square from which it attacks two or more enemy pieces at once, so the opponent cannot save them all.
Also called: knight double attack
The knight is the best forking piece because of the way it moves. It attacks in an L shape, so it can hit up to eight squares, and it jumps over pieces, so nothing can block the attack. A piece that the knight attacks cannot hit the knight back unless it is another knight, which makes the fork very hard to meet.
The strongest targets are the king, the queen and the rooks, and the best moment is when the targets are not protected well or the fork comes with check. Before you play a fork, make sure the knight is not simply captured on its new square and that your opponent has no check of their own that lets them escape first.
To find forks, look at the squares a knight can reach and count the enemy pieces on the squares it would attack from there. Pieces that stand two squares apart on the same rank, or a knight's distance from each other, are the classic targets. To avoid forks, check the squares around your pieces for enemy knights, and try not to leave two valuable pieces a knight move away from a single square, especially one you cannot control.
In the diagram White plays Nd5. The knight attacks the bishop on b6 and the rook on f6, and no Black piece can capture it on d5. If the rook moves, White plays Nxb6. If the bishop moves, White plays Nxf6+, a capture with check.
Also worth reading is Fork. A fork is a move that leaves one of your pieces threatening two enemy pieces together.
A neighboring idea is Opera mate. An opera mate is a back-rank checkmate in which a rook delivers mate on the eighth rank while a bishop guards that rook and also controls the square in front of the king.
A neighboring idea is Pawn fork. A pawn fork is a pawn move that attacks two enemy pieces at once, one on each of the two diagonal squares ahead of the pawn, so only one of them can escape.
To see how often "Knight fork" or a pattern like it decides your own games, book a first lesson: George Li reviews your games and writes a study plan around what he finds.
Related terms
A fork is a move that leaves one of your pieces threatening two enemy pieces together. Because the opponent gets only one turn to respond, something usually falls.
A royal fork is a fork that attacks the enemy king and queen at the same time, most often with a knight, so the king must move and the queen is lost.
A pawn fork is a pawn move that attacks two enemy pieces at once, one on each of the two diagonal squares ahead of the pawn, so only one of them can escape.
A double attack is one move that creates two threats at once, whether they come from a single piece or from two, and whether they aim at pieces or at checkmate.
Guides that go further
What to decide first, the questions to ask, what a first lesson should show and the red flags to avoid.
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