The gain of a Pawn is the smallest material advantage that can be obtained in a game; and it often is sufficient to win, even when the Pawn is the only remaining unit, apart from the Kings. It is essential, speaking generally, that the King should be in front of his Pawn, with at least one intervening square.
If the opposing King is directly in front of the Pawn, then the game cannot be won. This can best be explained by the following examples.
1.e3 Ke5. The position is drawn, and the way to proceed is for Black to keep the King always directly in front of the Pawn, and when it cannot be done, as for instance in this position because of the White King, then the Black King must be kept in front of the White King. The play would proceed thus: 2.Kd3 Kd5. This is a very important move. Any other move would lose, as will be shown later. As the Black King cannot be kept close up to the Pawn, it must be brought as far forward as possible and, at the same time, in front of the White King.
3.e4+ Ke5 4.Ke3 Ke6 5.Kf4 Kf6. Again the same case. As the White King comes up, the Black King must be kept in front of it, since it cannot be brought up to the Pawn.
6.e5+ Ke6 7.Ke4 Ke7 8.Kd5 Kd7 9.e6+ Ke7 10.Ke5 Ke8 11.Kd6 Kd8. If now White advances the Pawn, the Black King gets in front of it and White must either give up the Pawn or play 12.e7+, and a stalemate results. If instead of advancing the Pawn White withdraws his King, Black brings his King up to the Pawn and, when forced to go back, he moves to K in front of the Pawn ready to come up again or to move in front of the White King, as before, should the latter advance.
12…Ke8 13.Ke6. The whole mode of procedure is very important and the student should become thoroughly conversant with its details; for it involves principles to be taken up later on, and because many a beginner has lost identical positions from lack of proper knowledge. At this stage of the book I cannot lay too much stress on its importance.
In this position White wins, as the King is in front of his Pawn and there is one intervening square. The method to follow is to advance the King as far as is compatible with the safety of the Pawn and never to advance the Pawn until it is essential to its own safety. Thus:
1.Ke4 Ke6. Black does not allow the White King to advance, therefore White is now compelled to advance his Pawn so as to force Black to move away. He is then able to advance his own King. 2.e3 Kf6 3.Kd5 Ke7.
If Black had played 3…Kf5 then White would be forced to advance the Pawn to 4.e4+, since he could not advance his King without leaving Black the opportunity to play 4…Ke4, winning the Pawn. Since he has not done so, it is better for White not to advance the Pawn yet, since its own safety does not require it, but to try to bring the King still further forward.
4.Ke5 Kd7 5.Kf6 Ke8. Now the White Pawn is too far back and it may be brought up within protection of the King. 6.e4 Kd7 7.e5. Now it would not do to play 7.Kf7, because Black would play 7…Kd6, and White would have to bring back his King to protect the Pawn. Therefore he must continue, 7…Ke8. Had he moved anywhere else 7…Kd8, White could have played 8.Kf7, followed by the advance of the Pawn to e6, e7, e8; all these squares being protected by the King. As Black tries to prevent that, White must now force him to move away, at the same time always keeping the King in front of the Pawn.
8.Ke6. 8.e6 would make it a draw, as Black would then play 8…Kf8, and we would have a position similar to the one explained in connection with Example 5.
8…Kf8 9.Kd7. King moves and the White Pawn advances to e8, becomes a Queen, and it is all over.
This ending is like the previous one, and for the same reasons should be thoroughly understood before proceeding any further.