Rook vs Bishop: The Safe Corner
Black to play and draw
PlayA whole rook up, king on the sixth, and still your bare bishop holds. You are sitting in the one corner the rook cannot crack: the corner your bishop does NOT match.
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Rook vs Bishop: The Safe Corner
Hold the draw against perfect play
Waking the engine…
The theory
Rook versus bishop, no pawns, looks like a formality for the rook. It is a draw from almost everywhere, and the entire theory of the ending compresses into an estate agent's slogan: location. The defending king wants the corner whose color its own bishop cannot touch.
Why the mismatched corner holds. Trapped on h8 with a light-squared bishop, the defender always has the g8 interposition against the back-rank check. Capturing the bishop lets the king recapture with a trivial draw, and maintaining the pin backfires spectacularly: the pinned bishop cannot move, the king has no squares, and the defender is stalemated on the spot. The rook can win a tempo anywhere on the board except the one place it needs to.
Why the matching corner loses. Put the same king in a corner of the bishop's own color and the stalemate evaporates: the bishop now occupies the king's breathing square instead of guarding it, zugzwang arrives, and the rook collects the bishop or mates. One diagonal of difference separates a fortress from a funeral.
Practical value: this is the standard last-ditch save when an exchange goes down in a simplified position, and knowing WHICH corner to run to must be automatic, because the run starts many moves before the fortress forms. The tablebase attacker here will punish a single misstep of the bishop, which is the lesson: the fortress is solid, but only its exact furniture holds it up.