The strength or weakness of a pawn position, which, as we saw, had so deciding an influence in the end-game position just treated, is one of the most important factors in a game of chess, and should have full consideration in the middle game.  A pawn, when isolated, is naturally weaker than when it is or can be protected by another.  It may easily lead to the loss of a game, as the mobility of the King or a piece is reduced by having to protect the pawn (compare End-game, p. 102).

It is frequently and erroneously thought that doubled pawns as such are a weakness.  Doubled pawns are weak when isolated, for they cannot support each other.  But if doubled pawns can be supported by a pawn on the next file they need not by any means be at a disadvantage against three united single pawns on the opposite side.  For instance, in Diagram 64, if Black had a pawn at QKt3 instead of R2, White would have no winning chances.  He could not attack the pawns, nor would any kind of manoeuvres force a passed pawn through.  In the diagram, however, White wins through

---------------------------------------
8 |    |    |    |    |    |    |    |    |
|---------------------------------------|
7 | #P |    | #P | #K |    |    |    |    |
|---------------------------------------|
6 |    |    | #P |    |    |    |    |    |
|---------------------------------------|
5 |    |    |    |    |    |    |    |    |
|---------------------------------------|
4 |    |    |    | ^K |    |    |    |    |
|---------------------------------------|
3 |    |    |    | ^P |    |    |    |    |
|---------------------------------------|
2 |    | ^P | ^P |    |    |    |    |    |
|---------------------------------------|
1 |    |    |    |    |    |    |    |    |
---------------------------------------
A    B    C    D    E    F    G    H

Diag. 64

1.  K-B5; Black cannot then hold the pawn at B3. 1. ...  P-R3; 2.  P-Kt4.

In this particular case the win is made easy by the fact that the White King is able to attack the Black pawn at once.  But even without this advantage, the weakness of

---------------------------------------
8 |    |    |    |    |    |    |    |    |
|---------------------------------------|
7 |    |    | #P |    |    |    |    |    |
|---------------------------------------|
6 |    |    | #P | #K |    |    |    |    |
|---------------------------------------|
5 | #P |    |    |    |    |    |    |    |
|---------------------------------------|
4 | ^P |    |    |    | ^K |    |    |    |
|---------------------------------------|
3 |    | ^P |    |    |    |    |    |    |
|---------------------------------------|
2 |    |    | ^P |    |    |    |    |    |
|---------------------------------------|
1 |    |    |    |    |    |    |    |    |
---------------------------------------
A    B    C    D    E    F    G    H

Diag. 65

doubled pawns usually entails the loss of the game.  Diagram 65 may serve as an example.