Opposition (chess) - Diagonal Opposition

Diagonal Opposition

	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

Black to move. White has direct opposition, but it is not sufficient to win, it must be converted to diagonal opposition first.

	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

Black to move, White has diagonal opposition.

Opposition along a diagonal (instead of a rank or file) is called diagonal opposition. Sometimes diagonal opposition is used to achieve direct opposition. An example is the position in the diagram on the left, with Black to move. White has the direct opposition in this position, but it does him no good because his king cannot attack the black pawn after the black king moves away. White needs to achieve direct opposition closer to the pawn.

1. ... Kf8

2. Kd6 and White has the diagonal opposition (diagram on the right).

2. ... Ke8

3. Ke6 White now has direct opposition on a useful square, and White wins:

3. ... Kf8

4. Kd7 Kg8

5. Ke7 Kh8

6. f6 gxf6

7. Kf7 or 7. Kxf6 win for White (Flear 2004:33).