Key Square - Blocked Pawns

Blocked Pawns

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

Key squares for blocked pawns (white dots for the white king, black dots for the black king)

In a position with a blocked pair of pawns (opposing pawns on the same file), the key squares for a player's king extend for three files on either side of the opponent's pawn. In this position, the first king to reach one of his key squares will win the opponent's pawn and protect his own. Even though the white king is farther away from the pawns, White wins if he moves first:

1. Kg3! Kb7

2. Kf4 Kc7

3. Ke5 Kd7

4. Kd5 Kc7

5. Ke6 The white king reaches a key square.

5.... Kc8

6. Kd6 Kb7

7. Kd7 Kb8

8. Kc6 Ka7

9. Kc7 Ka8

10. Kxb6 and White wins (see king and pawn versus king endgame) (de la Villa 2008:172–73).

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

White to move, does not go directly to a key square

When both kings can reach a key square, a position of mutual zugzwang may occur. The first king to attack the opposing pawn must save a square for attack and defense (the squares marked "x"). With White to move:

1. Kd7! (The only winning move; all other moves lose. For instance, if 1. Kd6?? then 1... Kf5 puts White in zugzwang and Black wins)

1... Kf5

2. Kd6! (now Black in zugzwang)

2... Kg6

3. Kxe6 and White wins (de la Villa 2008:173).