Bähr's Rule: Winning the Queening Race
White to play and win
PlayWhen both sides are about to queen, the winner is decided by geometry, not counting. Bähr's rule: promote first and give a check that also wins the new enemy queen.
No signup needed. The opponent never gives up, and every mistake gets explained.
Bähr's Rule: Winning the Queening Race
Win against perfect defense
Waking the engine…
The theory
When both sides race to promote, the result often turns on a single tempo and the geometry of the board rather than on who counts fastest.
The rule. The side that queens first can frequently win the opponent's newborn queen with an immediate check: the check drives the enemy king in front of its own pawn or onto a square where a follow-up skewer or fork collects the queen. Bähr's rule tells you, from the pawns' files and the kings' positions, whether that decisive check exists.
What to look for. A rook's pawn and the queening square's colour, the diagonal from your promotion square to the enemy king, and whether your queen checks with tempo. If it does, the race is won even when the count looks equal.
In this drill both pawns are one step from queening. Promote with the check that wins, not the one that merely draws: the tablebase opponent will queen and defend perfectly if you misjudge the geometry.