Escape Squares, Support, and Blockers
Reading a mate means counting the king's escape squares first, then checking who supports the mating piece and what blocks each square. The rook on the back rank attacks the whole rank, and the king's own pawns fill the escape squares.
The finished shape
This is the finished shape. Reading a mate means counting the king's escape squares first, then checking who supports the mating piece and what blocks each square.
FEN: R5k1/5ppp/8/8/8/8/8/5K2 b - - 0 1
a b c d e f g h
8 R . . . . . k . 8
7 . . . . . p p p 7
6 . . . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 . . . . . K . . 1
a b c d e f g hThe worked example
White plays the mating move here. The rook on the back rank attacks the whole rank, and the king's own pawns fill the escape squares.
FEN: r5k1/5ppp/8/8/8/8/8/R4K2 w - - 0 1
a b c d e f g h
8 r . . . . . k . 8
7 . . . . . p p p 7
6 . . . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 R . . . . K . . 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: r5k1/5ppp/8/8/8/8/8/R4K2 b - - 0 1
a b c d e f g h
8 r . . . . . k . 8
7 . . . . . p p p 7
6 . . . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 . . . . . . . . 2
1 R . . . . K . . 1
a b c d e f g hKey points
- The rook on the back rank attacks the whole rank, and the king's own pawns fill the escape squares.
- The worked example ends with Rxa8.
- To prevent it, keep an escape square open for the king before the rook arrives.
- 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.
- A piece that fills an escape square is called a blocker.
Try it Yourself
Edit the code, then press Run.
Running is simulated · Rust Playground
Exercise
Find the checkmate in this position.