Guide · Tactics
Six Tactical Patterns Move Finders Spot Instantly
When you run a position through a move finder and the evaluation jumps by three points, there is almost always a tactic behind it. Most of those tactics are one of six shapes. Learn the shapes and you will see many of the engine's moves before it shows them.
Each diagram below was checked with Stockfish at depth 20, and every one opens in our move finder so you can test other moves. If you review your own games with ChessHelper (chesshelper.ai), the same six patterns are what its arrows point at most often in the positions where you went wrong; knowing their names makes those reviews much faster.
Why engines find tactics so easily
An engine looks at every legal move, including the ugly ones, and follows forcing sequences until the position is quiet. Humans prune: we ignore sacrifices and quiet moves that look odd. Tactics live exactly in those pruned branches. The cure is the habit from our method guide: list every check, capture and threat before choosing. Pattern knowledge tells you which of those forcing moves to calculate first.
| Pattern | Shape | Clue in the position |
|---|---|---|
| Fork | One piece attacks two targets | Two valuable pieces a knight's jump or a straight line apart |
| Pin | A piece can't move without exposing a bigger one behind it | King or queen on a line with a piece in front |
| Skewer | Attack the big piece; the one behind falls | King or queen in front of another piece on a line |
| Discovered attack | Moving one piece unmasks another | Your long-range piece aims through your own piece |
| Deflection | Force a defender away from its job | One enemy piece guards two things |
| Back-rank mate | Rook or queen mates on the last rank | King behind unmoved pawns with no escape square |
Fork
A fork is a single move that attacks two targets at once. The opponent can only save one. Knights are the classic forking piece because their jumps are hard to see, but queens, pawns and even kings fork too. The strongest forks include a check, since the opponent has no time to defend the second target.
Black is a queen against a knight, and it looks hopeless for White. But 1.Ne7+ checks the king on g8 and attacks the queen on c8. After 1...Kf8 2.Nxc8, White has won the queen; Stockfish rates the position +4.04, and every other move leaves White losing.
The clue: the king and queen both stood a knight's move from the same empty square, e7, which no black piece guarded. When two valuable pieces share such a square, look for the jump.
Pin
A pin attacks a piece that cannot move without exposing something more valuable behind it. If the piece behind is the king, the pin is absolute: moving the front piece is illegal. Pins win material when the pinned piece is worth more than the attacker, or when you can pile more attackers onto it.
1.Bc4 places the bishop on the same diagonal as the queen on d5 and the king on g8. The queen cannot leave the diagonal, because that would put its own king in check, so the best Black can do is 1...Qxc4 2.bxc4, giving the queen for a bishop. Stockfish: +3.33 for White. The pawn on b3 matters: without it the bishop would be lost for nothing.
Skewer
A skewer is a pin in reverse. The more valuable piece is in front; when it moves out of the attack, the piece behind it is captured. Long-range pieces (bishops, rooks and queens) create skewers, most often with a check.
The king on d5 and the queen on g8 share the a2-g8 diagonal. 1.Bb3+ checks the king, the king must step off the diagonal, and 2.Bxg8 wins the queen. Black cannot block, because the only square between bishop and king is c4 and no black piece reaches it. Stockfish gives the main line 1...Kd4 2.Bxg8 at +7.42.
Discovered attack
In a discovered attack, one piece moves out of the way and uncovers an attack by a piece behind it. The moving piece is free to make its own threat, so the opponent faces two at once. When the uncovered attack is a check, it is called a discovered check and is especially strong.
The rook on d1 aims at the queen on d8, but its own bishop blocks the file. Any bishop move unmasks the rook, and the question is which bishop move makes a threat Black must answer first. 1.Bxh7+ is the answer: a check, so Black has no time to save the queen. After 1...Kxh7 2.Rxd8, White is a rook up (+7.93). A quiet bishop move would simply let the queen escape.
Deflection
Deflection forces a defending piece away from the square or line it guards. Often the defender is overloaded: it guards two things, and you attack one of them so it has to abandon the other. A sacrifice that the defender must capture is the typical tool.
White's queen on g4 and bishop on h6 both aim at g7, and only Black's queen on f6 defends it. 1.Rd8+ attacks the back rank, and the only legal reply is 1...Qxd8, which pulls the queen away from g7. Then 2.Qxg7# is mate. Stockfish also finds 1.Qc8+ Qd8 2.Rxd8#, which exploits the same overloaded queen from the other side: it cannot guard g7 and the eighth rank at the same time.
Back-rank mate
A king behind its own unmoved pawns has no escape square. A rook or queen that reaches the back rank with check is then mate, unless another piece can block or capture. This pattern decides games at every level, and it is the reason players make a "luft" move like h3 or g6 when they have time.
1.Re8# is mate at once: the king cannot go to f8 or h8 (both on the rook's rank), and its own pawns block f7, g7 and h7. Black's rook on c2 is active but too far away to help. White's own king sits behind the same kind of pawn wall, which is why the rook on e1 was doing a useful job guarding the first rank before it moved.
Train the patterns with the finder
Pattern recognition grows from repetition. A useful routine:
- Open a diagram above in the finder, play a different first move, and press Find the best move for the defender. See how the engine refutes it.
- Press Show the threat in your own games before every critical move, and name the pattern behind the red arrow.
- Solve the practice positions without the engine, then check your answers.
- When you set up your own positions, the setup guide explains castling rights, side to move and the other details that change what the engine sees.
Fair play. Chess.com, Lichess, FIDE and US Chess forbid engine help during games. Use these patterns in your own head when you play, and the finder only for study and finished games.