25 years ago: Deep Blue beats Kasparov

by André Schulz
2/11/2021 – 25 years ago, on February 10, 1996, Deep Blue became the first chess computer to beat a reigning World Champion in a game under tournament conditions. This happened in the first Kasparov vs Deep Blue match, the first big "Man vs Machine" match. Despite his loss in the first game Kasparov still won the match 4-2, but one year later, 1997, he lost the rematch against Deep Blue.

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Computer beats World Champion

On March 1, 2021, the German Post will issue a special stamp "Deep Blue beats Kasparov". The stamp commemorates the first game of the first "Deep Blue vs Kasparov" match, in which the IBM machine became the first chess computer to beat a reigning World Champion in a game under tournament conditions. This happened on February 10, 1996.


Spiritus rector of the Deep Blue project was the programmer Feng-Hsiung Hsu. He and Murray Campbell started the project at Carnegie Mellon University. Later, Jerry Brody and Joe Hoane joined them. In 1989, the team took the project to IBM, where development continued under the direction of Dr Chun Jen Tan. One of the ideas was to significantly increase the speed of calculations by parallelising CPUs.

In 1993, experts at the ACM (Association of Computing Machinery) believed that a search depth of 14 half-moves could beat the best human players. In 1996, the IBM team thought their programme was sophisticated enough to challenge the reigning World Champion Garry Kasparov to a match. Kasparov's opponent was a colossus which was about two metres tall, weighed 700 kilograms, and could calculate 200 million positions per second. However, the "computing monster" was invisible to Kasparov.

The match between the supercomputer and Garry Kasparov took place in Philadelphia from 10 to 17 February – at least for the public. Kasparov sat at the Convention Center in Philadelphia in front of a chess board, and an operator transmitted the moves of the World Champion via keyboard to a computer. Then, the moves were sent via a telephone line to Yorktown Heights, New York State, where Deep Blue was calculating. After the machine had decided what to do, its move was sent back to Philadelphia and the operator made it on the board.

In his preparation for the match, Kasparov had considered ten different opening concepts with lines he usually did not play, because he assumed that the computer team had prepared their machine well for his usual openings. Kasparov's sparring partner was the ChessBase Windows program Fritz 4. In many training games against Fritz 4 the World Champion tried the openings he might want to play and then decided which of the lines he would actually use.

In the first game, Kasparov decided to play his favourite opening, the Sicilian. In the first two games he wanted to get to know the computer, preferably in the area he knew best himself. After the first game, however, Kasparov was very impressed by Deep Blue's playing strength, particularly by the move 23.d5! which he thought was a typical human move. After the defeat Kasparov spent a somewhat sleepless night and reconsidered his match strategy.

Basically, however, the strategy was clear. The battle had to be fought with long-term plans that the computer could not calculate. With subtle transpositions in the openings, Kasparov also quickly threw his opponent out of the opening library and made the machine calculate for itself as early as possible.

Kasparov then managed to win the second game after six hours of play with a strategically complicated Catalan and the World Champion became confident again. In the end Kasparov won the match 4:2. He won three games and two games ended in a draw.

Kasparov-Deep Blue 1996


The decade between 1996 and 2006 was an exciting time for the development of chess computers and computer programmes, and the "man versus machine" battle of wits captivated not only chess enthusiasts. Within their calculating horizon the machines made no tactical mistakes, but beyond their horizon they were practically blind, while humans could pursue long-term plans.

And the computers still fell for tricks, such as the small opening transpositions Kasparov used. But today, 25 years later, even world class players hardly have a chance against the programs. In 1996, thousands of spectators watched the match in the Philadelphia Convention Center, and several million followed the games on the internet, which was still in its infancy at the time.

Kasparov-Deep Blue, 1997

In 1997, a rematch took place, which attracted even more attention. Deep Blue had been further improved and this time Kasparov won the first game, but then resigned a drawn position in the second game. Kasparovs tried with all his might to win the match, but in the sixth game he went for a line in the Caro-Kann Defence that was considered to be bad if White was willing to sacrifice material. However, Deep Blue "knew" the refutation, sacrificed material, and won the game and the match.


In press conferences and interviews Kasparov had always declared that he was defending the "honour of mankind" against the world's best chess computer. After Kasparov lost the match, some professionals were not well disposed towards Kasparov. Viktor Kortschnoi commented bitingly: "Nobody asked Kasparov to play for the honour of mankind, and above all nobody asked him to lose it then."

As early as 2012, the Uganda Post Office dedicated a set of special stamps to the battle "Man vs Machine".


The post of Niger also issued a stamp about computer chess.

Translation from German: Johannes Fischer



André Schulz started working for ChessBase in 1991 and is an editor of ChessBase News.


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