Lesson of the Week
This diagram may be the single most import one for understanding elementary pawn endings. It is the key to understanding many complex pawn endings.
If it is White's move, White wins.
1.e7 Kf7 (only legal move) 2.Kd7 and the pawn promotes. The position can be shifted to the right or left, and the White king may stand on either side of the pawn. However, if the pawn is on a rook file (the a-file or h-file), the position is a draw.
If it is Black's turn, Black draws.
1...Kd8 2.e7+ Ke7 3.Kd6 stalemate.
As a practical matter, White may try to confuse Black by playing 2.Kc5, or other moves, aiming to triangulate and recreate this position with White to move. Black easily stops these ploys unless he or she becomes careless in time pressure.
The defender should keep in mind the king's idea position is directly in from of the pawn. When that is impossible, in front of the pawn with one intervening square, or in front of the king with one intervening square must be selected. As long as the diagram position with White to move is avoided, Black holds.
Another important pawn position may reach the first in some variations.
White wins no matter which player is on move.
With White to move:
1.Kd6 Kd8 2.e6 Ke8 and the first diagram is reached with White to move.
If 1...Kf8 or 1...Kf7 2.Kd7 supports the pawn for the last three squares of its journey.
With Black to move:
1...Kd8 2.Kf7 and the pawn has the support of its king.
A third diagram serves to illustrate how the first diagram is a foundation for more complex pawn endings.
If Black's h-pawn falls, the position is elementary. Hence the Black king must shuffle between g8 and h8.
Black to move, loses.
1...Kh8 2.h4 Kg8 3.h5 Kh8 4.g4 Kg8 5.g5 Kh8 6.g6
A form of the first diagram will be reached after 6...Kg8, or after 6...hxg6 7.hxg6.
If White moves first, it is necessary to move one of the pawns a single square on its first move in order to reach the last diagram with Black to move.