Clearance and interference: tactics about lines, not pieces
Two of the least-known tactics in chess and two of the most satisfying, because in both of them the piece that decides the game never captures anything.
- 120 positions in the course
- Difficulty 672–2311
- Section: Sharper Tactics
- 5 levels
What clearance and interference are
Clearance is moving one of your own pieces off a square or line so that another of your pieces can use it. Because the piece being moved is often thrown away with a sacrifice, the move looks absurd until you see what opens behind it.
Interference is the same idea aimed the other way: placing a piece in the middle of an enemy line to cut the connection between two of their pieces. The interfering piece is usually hanging, and usually cannot be taken without breaking something else.
How to spot it
- Ask which of your pieces would win immediately if a square were empty -- then look at what is standing on it. Frequently it is one of yours.
- For interference, find the two enemy pieces that are defending each other or a key square, and look at the squares between them.
- In both cases the candidate move usually hangs a piece. That is the signature, not a reason to reject it.
- These tactics live in sharp positions with long lines. If nothing is open, neither is on the board.
Three clearance and interference positions
Three positions from the 120 in this skill, easiest first. The highlighted squares are the move your opponent has just played. Work it out before you open the answer.
Position 1
White to move. Find the best move.
Show the answer
34...Ne5 35.Nf7+ Rexf7 36.Rg8#
The line ends in checkmate. The move that decides the position is about a line rather than a piece: one square is emptied or blocked, and everything else follows.
The position comes from an endgame of a real game, rated 672 for difficulty. The answer reaches checkmate.
Position 2
Black to move. Find the best move.
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28.Qf3 28...Rh1+ 29.Bxh1 29...Qh2#
The line ends in checkmate. The move that decides the position is about a line rather than a piece: one square is emptied or blocked, and everything else follows.
The position comes from the middlegame of a real game, rated 1347 for difficulty. The answer reaches checkmate.
Position 3
White to move. Find the best move.
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30...Nxf4 31.Qxa7+ Kd8 32.Qxb8+
The line wins a rook. The move that decides the position is about a line rather than a piece: one square is emptied or blocked, and everything else follows.
The position comes from the middlegame of a real game, rated 1885 for difficulty. The answer reaches a clear advantage.
Why these get missed
Because human candidate-move generation starts from targets. You look at what you can capture, check or attack, and a clearance sacrifice targets nothing at all -- it moves a piece to a square where it is simply taken.
The fix is a habit rather than a pattern: in a sharp position, once you have found the move that almost works, ask what is in the way, and include your own pieces in the answer.
Questions people ask
What is clearance in chess?
A move, often a sacrifice, that removes one of your own pieces from a square or line so a different piece of yours can use it. The sacrificed piece is not the point; the vacated line is.
What is interference in chess?
Placing a piece between two enemy pieces to cut the line connecting them, breaking a defence. The interfering piece is typically en prise, and capturing it usually re-opens a different line or costs more than it wins.
Nearby patterns
Clearance sits in Sharper Tactics. The rest of that section: