Perpetual check — what it means in chess
A draw forced by endless checks the opponent cannot avoid.
A draw forced by endless checks the opponent cannot avoid.
Perpetual check is an endless series of checks the defender can never escape — and in practice a draw, because the position repeats until the threefold repetition rule ends the game. It is the great equalizer of attacking chess: a player down a queen's worth of material can hold a draw if the enemy king can be checked forever.
The mechanism is almost always a shuttle: two check squares the defense cannot cover at once, visited in turn.
[[board startfen="r5k1/q4p1p/8/8/8/B5Q1/5PP1/7K w - - 0 1" pgn="1. Qb8+ Kg7 2. Qe5+ Kg8 3. Qb8+ Kg7 4. Qe5+ Kg8 5. Qb8+ Kg7 6. Qe5+ Kg8" caption="The shuttle: two check squares the defense can never cover, and the position repeats to a draw." notes="White to move, and hopelessly behind: Black has an extra queen and rook. But the White queen has two squares. Qb8+ — check along the back rank. The bishop on a3 seals f8, so the king has one reply. Kg7 — the only move. Qe5+ — check on the long diagonal, and again there is exactly one answer. Kg8 — back home. Qb8+ — the shuttle repeats. Kg7 — as before. Qe5+ — and again. Kg8 — the position has now occurred twice. Qb8+ — a third visit. Kg7 — no way off the treadmill. Qe5+ — the same position is about to appear a third time. Kg8 — threefold repetition: the game is a draw, and the extra queen and rook never mattered."]]
For the attacker a perpetual is an insurance policy — the escape hatch that makes speculative sacrifices playable. For the defender, the lesson is about the king's shelter: a check that cannot be met by a block or capture, from squares that alternate, is a draw the material count cannot veto.
The Endgame Society glossary defines more than 240 chess terms — rules, notation, tactics, strategy, pawn structures, endgames, and openings — in language a beginner can act on rather than dictionary shorthand.