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The Dictionary of Endgame Theory: Essential Positions & Rules
"The opening is memorization, the middlegame is imagination, but the endgame is calculation." This glossary defines the precise theoretical positions and rules you must know to convert a win or save a draw.
1. King & Pawn Fundamentals
Rule of the Square
A geometric shortcut to determine if a King can catch a Passed Pawn without calculating move-by-move. Imagine a square box extending from the pawn to the promotion rank.
The Rule: If the King can step into the square, he catches the pawn. If not, the pawn promotes.
Opposition
A situation where the two Kings face each other with one square in between. The player NOT to move "has the opposition" (a positional advantage).
Why: It forces the enemy King to step aside, allowing your King to invade (outflanking).
Key Squares
Specific squares in front of a pawn that guarantee a win if your King occupies them, regardless of whose turn it is.
The Rule: For a non-rook pawn, getting your King to the 6th rank in front of the pawn usually wins.
Triangulation
A maneuver where the King moves in a triangle shape (e.g., d5-e5-d4) to return to the same square but "lose a tempo," passing the move to the opponent.
Goal: To put the opponent in Zugzwang.
Trebuchet
A situation of "Mutual Zugzwang." Whoever has to move loses their pawn. Neither King wants to move.
2. Rook Endings (Most Common)
Lucena Position
The "Mother of All Endgames." You have a Rook and a Pawn on the 7th rank, but your King is trapped in front of it. You must build a "Bridge."
The Technique: Use your Rook to cut off the enemy King, then bring your King out, using your Rook as a shield against checks.
Philidor Position
The essential defensive technique to draw Rook vs Rook + Pawn. The defender keeps their Rook on the 6th rank to stop the enemy King from advancing.
The Trick: When the pawn advances to the 6th rank, the defender immediately moves the Rook to the back rank to check the King from behind.
Vancura Position
A specific defensive setup for Rook + Rook Pawn endings where the defender attacks from the side (the "Long Side") to secure a draw.
Checking Distance
The required distance (usually 3 files/ranks) between a Rook and an enemy King for checks to be effective. If too close, the King attacks the Rook.
3. Minor Piece Endings
Wrong Colored Bishop
An ending with a Bishop and a Rook Pawn (a or h file). If the Bishop is on the opposite color of the promotion square (corner), it is a draw if the enemy King reaches the corner.
Why: The Bishop can never chase the King out of the corner.
The Centaur
A nickname for a Bishop + Knight combination. They cover both light and dark squares perfectly, often stronger than a Rook in the endgame.
Barrier (Knight)
A Knight can create a "barrier" of controlled squares that an enemy King cannot cross, often used to stop a King from supporting a pawn.
4. Universal Concepts
Fortress
A setup where the weaker side sets up an impenetrable defensive zone. Even if down material (e.g., Queen vs Rook), the opponent cannot break through.
Principle of Two Weaknesses
In the endgame, one weakness (like a bad pawn) is usually defendable. To win, you must create a second weakness on the other side of the board to stretch the defender.
Zugzwang
A German term meaning "compulsion to move." A situation where every legal move available to a player worsens their position. They lose because they cannot pass.