Corresponding Squares in Pawn Endgames

Watch the method: press play to see the winning idea run, or step through it move by move.

Opposition is the simplest case of a much deeper idea. When pawns lock the position and both kings maneuver, every important square for the attacking king has a matching square the defender must occupy in reply. Map those pairs and the ending plays itself; miss them and you shuffle forever.

The method. Start from the squares where the breakthrough happens: the square from which your king wins a pawn or escorts its own. For each of those, find the unique defensive square. Then work backwards: a square whose neighbors need answers from squares that are not neighbors of each other is a second layer of the network. The attacker wins by arriving at a network square when the defender cannot reach his partner square in time.

Why retreating wins. The attacking king usually has more room, so it can travel between its network squares along spare paths while the cramped defender has exactly one route. The winning maneuver in this drill starts with a step backwards, a move no material-counting instinct would ever suggest. The tablebase confirms it: the direct approaches only draw.

Where you will use it: any blocked king and pawn ending, which is where a huge share of middlegame simplifications land. This position is small enough to calculate honestly and rich enough to force the full method.