Endings 4 & 5
Distant opposition as a defensive tool, reserve pawn moves as a tempo-losing weapon, the special drawing rules of the rook's pawn, and how the defending king can imprison the stronger king near the edge.
For a 4th-rank pawn, the key squares are two ranks ahead: b3, c3, and d3. Sometimes opposition alone is not enough. The defender can use distant opposition to prevent the attacking king from reaching the key squares.
Position 1.12 · The distant opposition · White to move
FEN: 8/8/8/1kp5/8/8/8/K7 w - - 0 1 · Key squares: b3, c3, d3
When both kings stand on the same file separated by an odd number of squares, they have distant opposition. Although Black can advance one rank, he cannot make further progress because White will immediately take the direct opposition.
Distant opposition, like direct opposition, can be lost when important squares are unavailable.
Winning move
Main line
Variation
The white king already occupies the key squares, but he still needs to outflank the opposing king. This becomes possible because White has a reserve move with the pawn.
Position 1.13 · Using reserve moves · White to move
FEN: 8/6k1/8/6K1/8/6P1/8/8 w - - 0 1 · Key squares: f5, g5, h5
By advancing the pawn, White gives the move to Black while preserving the winning king position.
Winning move
Main line
Everything learned so far applies to every pawn except the rook's pawn. Because of stalemate possibilities, rook's pawns require special treatment.
If the defending king stands directly in the pawn's path, the game is drawn regardless of whose move it is.
Position 1.14 · The rook's pawn: defending king in front of the pawn · White to move
FEN: 8/8/8/8/8/6kp/8/6K1 w - - 0 1
The black king on g3 stands directly in the path of the h-pawn. No matter what White tries, the pawn cannot promote.
Main line
This imaginary position illustrates how powerful the drawing mechanism is. Even six connected rook's pawns cannot overcome the defending king when it occupies the critical square.
Position 1.15 · Quantity is not quality · White to move
FEN: 8/7p/7p/7p/7p/6kp/7p/6K1 w - - 0 1
The black king on g3 blocks the path of all the h-pawns. White has six rook's pawns, yet none can promote.
Demonstration
If White tries a different pawn:
Or:
The stronger side must eventually give up every pawn or remain unable to advance because every attempt ends in stalemate.
Standing in the pawn's path is not the defender's only drawing method. Near the edge of the board, the defending king can imprison the stronger king and prevent progress.
Black threatens ...Kb2, which would secure the pawn's promotion. White must react immediately.
Position 1.16 · Imprisoning the stronger side's king · White to move
FEN: 8/8/8/8/p7/1k6/3K4/8 w - - 0 1 · Key squares: c1, c2
The black king on b3 threatens ...Kb2, which would secure the pawn's promotion. White must react immediately.
Drawing move
White prevents ...Kb2 while threatening Kb1. The white king heads for the key squares c1 and c2 to block the black king's path.
Continuation
This is a transition to the next section. The detailed continuation of the imprisonment theme follows in the next lesson.