Interrupting the line of communication between an enemy defensive piece and its target by physically inserting a piece directly in between them.
Why it matters
Interference cuts a defender off from what it is defending by putting something in the way — often a piece the defender can simply take, which is the point: taking it costs a move and blocks the line anyway.
It looks absurd on the board, which is why it is so often missed: nobody expects a piece to be dropped onto an empty square between two enemy units.
See it on a board
Two rooks on the same open file. Whatever lands between them cuts the line each one depends on — which is the whole idea of interference.
Checked: this line wins at least 5 pawns of material.
How to play it
- White plays d5!.
- By placing a pawn on d5, White cuts the 4th-rank line of communication between the a4-queen and the f4-bishop.
- If Black takes the pawn, the line remains blocked long enough for White to capture the bishop.
At each level
The same idea, said the way it is taught at each age.
Bishop · ages 5–7
If a piece is defended along a line, look for a square in the middle of that line where you could put something. Cutting the line is as good as taking the defender.
Rook · ages 6–9
Interference is the hardest tactic to see because the interfering move often hangs a piece. Check forcing moves that land between two enemy pieces, not just captures.
What goes wrong
- Interfering on a line the defender was not actually using.
- Missing that the blocking piece can be captured by something other than the defender.
Questions people ask
- What is the difference between interference and blocking?
- Interference cuts a defender off from what it guards. Blocking gets in the way of a pawn or a king's escape square. The idea is the same: occupy a square that mattered.