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The Windmill

A windmill is a repeating discovered check. A rook captures, a bishop gives check, the king moves, and the rook captures again.

A windmill wins two pieces

The rook on g7 blocks the bishop on c3. The rook captures the pawn on a7 and uncovers a check on the king on h8. The king moves to g8, and the rook captures the pawn on a2.

FEN: 7k/p5R1/8/8/8/2B5/p7/6K1 w - - 0 1

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

A windmill check from a diagonal battery

The rook on f7 blocks the bishop on a2. The rook captures the pawn on a7 and uncovers a check on the king on g8 along the diagonal. The king must move.

FEN: 6k1/p4R2/8/8/8/8/B7/6K1 w - - 0 1

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

Key points

  • A windmill needs a rook and a bishop working together.
  • The bishop aims at the enemy king through the rook.
  • The rook captures a piece and uncovers a check.
  • The king must move, so the rook is free to capture again.
  • The rook returns and captures another piece.
  • Each cycle wins another piece.
  • A windmill ends when the king escapes or the rook is captured.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Rust Playground

Exercise

White to move. Which move starts the windmill and wins material?