Chess lessons › Chess endgames
The rule of the square
Can the king catch the pawn? Draw a square from the pawn to the queening square.
The idea
A king inside the pawn’s square catches it; outside, the pawn queens.
- Draw a square from the pawn to its queening square.
- It is White’s move, and Black’s king is inside the square.
- So the king is in time to catch the pawn.
In a game: When a passed pawn runs, picture its square and see if the other king is inside.
The lesson
Can a lone king catch a pawn that is running to queen? You can tell without counting every move. Draw a square from the pawn to the queening square. The pawn on e5 needs three moves to reach e8, so the square is four squares wide: b5, e5, b8 and e8 are its corners.
If Black’s king is inside the square when it is White’s move, the king can catch the pawn. Here it stands on b7, inside, and White’s king is far away. Watch.
- 1. e6 The pawn runs.
- 1... Kc7 The king heads for e8.
- 2. e7 Kd7 The king arrives next to the pawn and the queening square just in time.
- 3. e8=Q+ Kxe8 The king takes the new queen. Only the two kings are left: a draw.
Now Black’s king is on a6, one file outside the square. It cannot reach e8 in time, so the pawn simply runs. The same square is marked.
- 1. e6 The pawn runs.
- 1... Kb6 The king follows, but it is a move behind.
- 2. e7 Kc7 3. e8=Q The pawn queens, and the king is too far away to take it.
Find the move
Black’s king is on a7, outside the square, but this time it is Black’s move. Can it still save the game? Step into the square.
A hint
The left edge of the square is the b-file. Step onto it.
Show the answer
1... Kb6
Any of Kb6, Kb7 and Kb8 works: the king is inside the square and White is to move, so the king catches the pawn. A move like Ka6 stays outside, and then the pawn queens, as you saw before.
Find the move
Same position, but now it is White’s move. The king is outside the square. Only one move wins. Do not wait.
A hint
Move the pawn, not the king.
Show the answer
1. e6
e6. The king is outside the square, so the pawn queens if it runs now. If White waited, Black would be on the move, and a king to move can step into the square.
Find the move
Black to move. The king is on a4, just below and outside the square. Only one move saves the game. Find the corner of the square.
A hint
The lowest corner of the square is on the fifth rank.
Show the answer
1... Kb5
Kb5 is the bottom corner of the square, and the king gets there in one move. If White runs, the king follows with Kc6 and Kd7 and catches the pawn. Every other move leaves the king outside the square, and the pawn queens.
Play it out
Now the other way round. The pawn on d5 needs three moves, so its square is d5 to g8, four squares wide. Black’s king is on h7, outside it, but it is Black’s move. Step into the square and hold the draw.
In the lesson you play this out on the board, against the endgame tablebase’s best defence.
Practise
A pawn far down the board decides many games. Here are some from real play. Ask yourself what the pawn needs, and who can stop it.
In the lesson, 5 rated puzzles on this theme come from the puzzle bank, chosen near your rating.
In numbers
Positions to practise
120 positions in the study, every result proved by the tablebase: 41 are wins, 59 draws and 20 losses for the side to move, with best play on both sides.