King & Pawn Endgame Notes

Endgame Prerequisites

Before any particular endgame can be studied a few board/piece/space definitions must be established.

The Pawn's Universe	A Passed Pawn	Doubled Pawns	Kings in Opposition

1. The Pawn's Universe consists of the pawn's file and the adjacent files on either side.

2. A Passed Pawn is a pawn with no opposing pawns in it's universe. An important advantage for the endgame can be gained by creating one or more passed pawns during the midgame.

3. Doubled Pawns are pawns of the same color which are on the same file. Typically, this is very awkward and unweildly.

4. Kings in Opposition are forced to retreat, this is a key element in many endgames. The king which is pushing the other king back 'has' the opposition, the king which has to move is 'in' opposition.

The Square of the Pawn	The Critical Diagonal

4. The Square of the Pawn is an imaginary square area to the front of a pawn which is described by the pawn's Critical Diagonal. If an opposing king can enter this square, he can capture an unaided pawn before it promotes.

5. The Critical Diagonal runs from the pawn in question to the back row. (If the pawn is still on it's starting square, start on the next square.) The Square of the Pawn is drawn to encompass this diagonal. Note in the diagram above, that the Black king is in the square and will win the pawn unless the White king aids the pawn.

Exercise - Try this out. You should be able to know from a glance whether or not an unsupported pawn will be able to outrun and enemy king. Play out your own setups and and prove it to yourself!

The proper moves for White from this position are Ke3, Kd4, Kc5, Kb6, ... c5, c6, c7, c8=Q, but depending on how black plays there are multiple opportunities for stalemate traps! Also note that if the requirement for king support is not recognized immediately and the pawn moves before the white king, then a win becomes impossible without errors from black.