Spotting a Mate One Move Early
Spotting a mate one move early means seeing the final move before you play it, and checking the escape squares first so the mate is real. The queen steps to the edge square, and the white king protects it, so the king cannot take it.
The finished shape
This is the finished shape. Spotting a mate one move early means seeing the final move before you play it, and checking the escape squares first so the mate is real.
FEN: k7/1Q5p/1K6/8/8/8/8/8 b - - 1 1
a b c d e f g h
8 k . . . . . . . 8
7 . Q . . . . . p 7
6 . K . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . . . . 1
a b c d e f g hThe worked example
White plays the mating move here. The queen steps to the edge square, and the white king protects it, so the king cannot take it.
FEN: k7/4Q2p/1K6/8/8/8/8/8 w - - 0 1
a b c d e f g h
8 k . . . . . . . 8
7 . . . . Q . . p 7
6 . K . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . . . . 1
a b c d e f g hHow to prevent it
Black plays h6 first. The pawn move opens an escape square, so the mate no longer works.
FEN: k7/4Q2p/1K6/8/8/8/8/8 b - - 0 1
a b c d e f g h
8 k . . . . . . . 8
7 . . . . Q . . p 7
6 . K . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . . . . 1
a b c d e f g hKey points
- The queen steps to the edge square, and the white king protects it, so the king cannot take it.
- The worked example ends with Qb7.
- To prevent it, keep the king off the edge or keep an escape square open.
- Black plays h6 first. The pawn move opens an escape square, so the mate no longer works.
- Check every escape square before you play the mating move, because one open square breaks the mate.
Try it Yourself
Edit the code, then press Run.
Running is simulated · Rust Playground
Exercise
Find the checkmate in this position.