🎓 A1Learner
🔍
0 of 43 lessons completed

Interference

Interference places a piece between a defender and the piece it defends. The line is cut, and the defended piece falls.

A pawn interferes with a queen's defence

The queen on d8 defends the knight on d4 along the file. The pawn on c5 captures the pawn on d6 and blocks the file. The white queen then captures the knight on d4.

FEN: 3qk3/8/3p4/2P5/3n4/8/8/3Q2K1 w - - 0 1

a b c d e f g h
8 . . . q k . . . 8
7 . . . . . . . . 7
6 . . . p . . . . 6
5 . . P . . . . . 5
4 . . . n . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . Q . . K . 1
  a b c d e f g h

A bishop interferes with a rook's defence

The rook on a8 defends the queen on a5 along the file. The bishop moves from c4 to a6 and blocks the file. The rook moves to b8, and the white queen then captures the queen on a5.

FEN: r3k3/8/8/q2Q4/2B5/8/8/6K1 w - - 0 1

a b c d e f g h
8 r . . . k . . . 8
7 . . . . . . . . 7
6 . . . . . . . . 6
5 q . . Q . . . . 5
4 . . B . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . . K . 1
  a b c d e f g h

Key points

  • A defender guards a piece along a line.
  • The attacker places a piece on that line.
  • The line is blocked, so the defence is cut.
  • The defended piece can then be captured.
  • Interference works on ranks, files, and diagonals.
  • A knight is a good interfering piece, because it cannot be captured along the line.
  • A pawn is a good interfering piece, because it is cheap.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Rust Playground

Exercise

White to move. Which pawn move interferes with the queen on d8's defence of the knight on d4?