In 1946,
Alexander Alekhine died while still holding the title of World Chess Champion. The
International Chess Federation (FIDE), which had been founded in 1924, had been attempting to directly participate in organizing the World Championship since at least 1935. By the late 1940s, around half of the plausible contenders for the World Championship were
Soviet citizens, and in 1947, the
Soviet Chess Federation joined FIDE after decades of declining to do so. FIDE based the
1948 World Chess Championship on the 1938
AVRO tournament that had been organized in part to select a challenger for Alekhine. The tournament ultimately featured five players, three of them Soviet citizens—including the winner,
Mikhail Botvinnik. Botvinnik went on to win or retain in four further championship matches. At the same time, FIDE established the rules for the championship going forward. It was organized around a 3-year cycle, during which a series of
Zonal and Interzonal tournaments were held, with their highest-scoring performers invited to a
Candidates Tournament. The winner of the Candidates tournament in turn played the champion in a match for the title. A defeated champion was entitled to a rematch the following year, after which the 3-year cycle would resume. Botvinnik benefited from this rule twice, in 1958 and 1961. With the exception of the American
Bobby Fischer in 1972, Soviet citizens won every championship from 1948 until the
dissolution of the Soviet Union in 1991. With the further exception of
Viktor Korchnoi, who had defected from the USSR in 1976, each challenger was also a Soviet citizen. Following
his victory, Fischer never played another game organized by FIDE. Disagreements between the two parties—which included Fischer's insistence on a format that required the victor to get a certain number of wins, as opposed to the number of games in a match being fixed—led to his forfeiting the title in 1975. In the absence of a match, FIDE declared
Anatoly Karpov, winner of the 1974 Candidates Tournament, to be the World Chess Champion by default. While the issue had played a role in Fischer's forfeit, FIDE ultimately did change the match format going forward, such that the first to win 6 games would be champion. Under these rules, Karpov twice defended his title against Korchnoi. The
next match—which began in September 1984 and featured the 21-year-old
Garry Kasparov as Karpov's challenger—ultimately saw 48 games played over the span of five months, with neither player able to get to 6 wins. In an unprecedented step, FIDE president
Florencio Campomanes stepped in and declared the match to have ended with no result. A
new match, reverted to having a set number of games, was to be played later in 1985. After nearly being knocked out early in 1984, Kasparov defeated Karpov in their rematch. Over the following decade, the two played three more championship matches, with Kasparov narrowly retaining the title in each. == Split title (1993–2006) ==