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Opposition

Opposition means the kings face each other with one square between them. The side not to move holds the opposition.

Kings face each other

White king is on e5 and Black king is on e7. One square, e6, stands between them, so the kings are in opposition.

FEN: 8/4k3/8/4K3/8/8/8/8 w - - 0 1

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

White must step aside

White is to move in opposition. White plays Kf5 and steps aside, so Black keeps the opposition.

FEN: 8/4k3/8/4K3/8/8/8/8 w - - 0 1

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

Black must step aside

Black is to move in the same position. Black plays Kd7 and steps aside, so White keeps the opposition.

FEN: 8/4k3/8/4K3/8/8/8/8 b - - 0 1

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

Key points

  • Opposition happens when the kings stand on the same file or rank with one square between them.
  • The side to move must step aside and give ground. The side not to move keeps the opposition.
  • Opposition matters in king and pawn endgames. The side with the opposition can often force the enemy king back.
  • Take the opposition by moving your king to face the enemy king. One square between the kings is the key distance.
  • Losing the opposition means stepping aside. A king that steps aside lets the enemy king advance.

Try it Yourself

Edit the code, then press Run.

Running is simulated · Rust Playground

Exercise

White king is on e5, Black king is on e7, and White is to move. Who holds the opposition?