+---------------------------------------+
8 |    |    |    | #R |    |    | #K |    |
|---------------------------------------|
7 | #P |    |    |    |    | #P | #Q | #P |
|---------------------------------------|
6 |    | #P |    |    |    |    | #P |    |
|---------------------------------------|
5 |    |    | #P |    | ^R |    |    |    |
|---------------------------------------|
4 |    |    |    |    |    |    |    |    |
|---------------------------------------|
3 | ^P |    |    |    | ^Q |    |    |    |
|---------------------------------------|
2 |    | ^P | ^P |    | ^K | ^P | ^P | ^P |
|---------------------------------------|
1 |    |    |    |    |    |    |    |    |
+---------------------------------------+
a    b    c    d    e    f    g    h

Diagram 58.

For the time being Black has the opposition so that White’s King cannot advance any further; but White has so many more Pawn moves at his disposal than Black that the latter is soon forced to move his King allowing White to break in with his King at one or the other side.  For instance:  (7) P-a4, P-a5; (8) P-f4, P-f6; (9) P-g4, P-h6; (10) P-h3, P-g5; (11) P-f5; King moves, and White wins either the f-Pawn or the b-Pawn.

This example brings out another reason why it is advantageous to keep the Pawns of the wings back.  In the ending positions frequently arise in which it is important to have some moves to spare in order to be able to maintain the opposition of Kings; and the player whose Pawns are farther back naturally has more spare moves.

A disadvantage which is liable to make itself felt in the middle game as well as in Rooks’ endings as a consequence of Pawn moves on the wing is the opening of an adjoining file for a hostile Rook, as illustrated by the play in the positions of Diagrams 50, 51 and 54.  In the middle-game this is also true of certain Pawns, as for instance in the following position which arises after the opening moves (1) P-e4, P-e5; (2) Kt-f3, Kt-c6; (3) P-d4, Pxd4; (4) B-c4, Kt-f6; (5) o-o, B-e7.  The proper continuation is (6) R-e1, protecting the center-Pawn.  The advance of this Pawn is entirely uncalled for.  Not only does it enable Black to open the f-file for his Rook by advancing his f-Pawn, but it gives up the greatest advantage connected with the possession of a center-Pawn, that is the control of two center-squares.  As long as White has his Pawn on e4, the two squares f5 and d5 are inaccessible to black pieces; as soon as the Pawn advances, however, he does not do Black any further harm, as the two squares which he controls after the advance are firmly in Black’s hands on account of the two Pawns f7 and d7.