When one side has a pawn and the other does not, what decides the game is the the promotion of the pawn. To win or draw the game, the crucial question is:
Can the pawn promote?
To answer the question, we must examine a number of positions. The simplest case occurs when the opponent king may or may not be too far from the pawn to prevent its promotion. While these endings can be calculated manually every time, the rule of the square is a safe and quick way to answer the question “can my pawn queen on its own or will the opponent king catch it?”.
When the pawn cannot run to promotion without its own king support, the positions are generally more complicated so we’ll break the problem down in topical positions.
Let’s start with the rook pawn. Here’s a position that shows the main ideas behind this ending:.
If white to move, the pawn promotes because the position presents both critical aspects:
- the white king occupies the
b7square from where it can support the promotion.
- the black king cannot pose any danger to the pawn.
It’s worth noticing that the same exact position with black to move is a dead draw (because the black king can catch the pawn unopposed).
Here’s a similar position where the result is a draw because the white king
cannot get to
The rest of the pawns are considerably stronger than the rook pawns. Defending is much harder as the stronger side has more resources they can use in order to promote the pawn. Let’s start with a topical sequence:
There are a couple of things to notice:
- If the stronger side can reach this position, it’s always a win no matter who’s to play the next move.
- Having the king in front of the pawn is vital for supporting promotion.
Maybe a little harder to see but the most important point: this procedure only works on the sixth rank. Let’s see why:
A beautiful stalemate position.
Two concepts are at play here:
- Opposition Gaining opposition at the right time is the key to both attack and defense in this ending.
- key squares In order to clear the path to promotion, the stronger king must occupy one of the three key squares.
Now that we have seen different cases, we can put together a strategy:
- Being in front of the pawn increases the chances of promotion significantly.
- The stronger side must occupy a key square to support promotion.
As you can see, despite the very little material on the board, there are many things to take into account. That’s the blessing and the course of endgame study.