The Machine Wins

The sixth and final game of the 1997 rematch between Kasparov and IBM's Deep Blue lasted barely an hour and settled the first match a reigning World Champion ever lost to a computer under normal time controls. Kasparov chose a Caro-Kann, and Deep Blue answered with the sacrifice 8.Nxe6!?, giving up a knight to shatter Black's kingside pawns and drag his king into the centre.

Kasparov, by his own account rattled by the sacrifice and suspicious that the machine's play looked unusually human, never found his footing afterward; his position deteriorated quickly and he resigned after only nineteen moves, the shortest defeat of his professional career at that level. The abruptness of the collapse, and Kasparov's later suggestion that IBM's team might have received human assistance during the match, a claim IBM always denied and that independent analysis has never supported, kept the result controversial for years.

Whatever the truth of Kasparov's suspicions, the game itself marked a turning point: after Deep Blue's win, computer assistance stopped being a curiosity in chess and became, within a decade, simply how the game is trained and analysed at every level.