No individual made a more profound impact on world history in the second half of the 20th century than did Mikhail Gorbachev, the last leader of the Soviet Union. The celebration of his 90th birthday on March 2 is a time to reflect on the difference he made and to dispel misconceptions.

In 1985 the Soviet Union was a military superpower just as capable of destroying the United States and Western Europe as NATO was of devastating the USSR. No amount of outside pressure could force a Soviet leadership to take concrete steps to end the Cold War, to replace obligatory Marxist-Leninist official doctrine with free intellectual inquiry, and to transform the political system. The popular notion that it was the defects (real enough) of the Soviet economy that impelled radical change is belied by the higher priority that Gorbachev gave to political rather than economic reform.

Many senior members of the Reagan administration—though not his secretary of state, George Shultz—came to believe that Gorbachev was simply bowing to the inevitable and doing what any Soviet leader would have to do when confronted by the American arms buildup and ideological offensive. US Defense Secretary Caspar Weinberger was prominent among those who, even in retrospect, failed to understand Gorbachev’s contribution and his values. As Weinberger saw it, Gorbachev realized that the Soviet Union “couldn’t win a war,” so he changed his rhetoric, but not his philosophy: “He talked a lot about perestroika, glasnost, all of those things, but he never really changed.”

That was wildly wrong. Luckily, Reagan had confidence in his own impressions of Gorbachev and preferred the judgment of Shultz on the need for constructive dialogue with the Soviet Union to Weinberger’s deep suspicion of any such contacts. The leadership of the CIA was no less obtuse than the Defense Department.

Nothing could be further from the truth than the assertion that Gorbachev did not change. His political views underwent a remarkable evolution. He had an unusually open mind for a political leader, to say nothing of a general secretary of the Communist Party of the Soviet Union. He began in 1985 as a Communist reformer and before the end of the decade had evolved into a socialist of a social democratic type—on the same wavelength as his favorite foreign interlocutors, Spanish Prime Minister Felipe González and president of the Socialist International and former West German chancellor Willy Brandt.

The destructive power at the disposal of American presidents and Soviet leaders gave the relations between them a unique significance. Reagan, with the encouragement of Shultz and the foreign leader he called his “soulmate,” Margaret Thatcher, was prepared to engage with Gorbachev. Their disagreements were vast, but they shared a desire to outlaw nuclear weapons entirely, a policy that disturbed the Washington foreign and defense establishment more than it did their Moscow counterparts, for the Soviet side retained an advantage in conventional forces.

That objective also horrified the British prime minister. Thatcher thought that the only good thing about the 1986 Reykjavik summit at which the two leaders came close to banishing nuclear weapons was that it ultimately foundered on the rock of Reagan’s obsessive attachment to developing an anti-missile defense system, his so-called Strategic Defense Initiative, or SDI. But American triumphalist accounts that credit Reagan, and even SDI specifically, for leaving the Soviet leadership with no alternative to pursuing a concessionary peace policy are wide of the mark.

Four different Soviet top leaders occupied the Kremlin during Reagan’s presidency. His first two years coincided with Leonid Brezhnev’s last two. Then came the 15 months of Yuri Andropov, followed by Konstantin Chernenko’s 13 months, leading Reagan to complain that “these guys keep dying on me.” Different from each other as those three Soviet leaders were, none of the fundamentals of the Soviet system changed during their leadership and the Cold War stayed icy. It was not until Gorbachev succeeded Chernenko on March 11, 1985, just nine days after his 54th birthday, that serious change got underway.

Gorbachev seized the initiative when Chernenko died at 7:20 pm on March 10, convening and presiding over a Politburo meeting that very same evening. The next day his selection by the Politburo as general secretary was endorsed by the Central Committee. Neither body knew how far he was prepared to go, nor, for that matter, was Gorbachev himself aware in March 1985 of how far he would move in transforming the political system and Soviet foreign policy, but he knew it was further than anything in the minds of those who sat around the same table.

Psychologically, the characteristics of the new leader that made the scale of change possible were his intelligence, openness to new ideas, a natural charm which enabled him to establish a rapport with diverse leaders and groups, and an inborn optimism. Only an optimist would have challenged the most powerful institutional interests within the Soviet system, including the military-industrial complex. Gorbachev’s mindset was different from that of other surviving members of the old guard. Nikolai Ryzhkov, chairman of the Council of Ministers from 1985 to 1990, described him as “an alien in Brezhnev’s Central Committee,” For Anatoly Gromyko, son of the long-serving Soviet foreign minister, Gorbachev was a “pacifist.” That was an exaggeration, but he was without doubt the most pacific leader in Soviet history.

Politically, what made it possible for Gorbachev to introduce so much change in the Soviet system was the power vested in the office of general secretary. But that power was great so long as the leader did not undermine the pillars of the system. These were the Communist Party’s monopoly of power, which meant a ban on the formation of any independent organizations; ‘democratic centralism,’ a euphemism for a highly centralized party with strict discipline imposed from above and the absence in reality of democratic debate; the power accorded the KGB to root out and punish any organized dissent; strict censorship of books and the mass media; and pseudo-elections with only one candidate to “choose” from. In a strictly hierarchical ruling party possessing unchallengeable power, the person at the top of that hierarchy—the general secretary—wielded immense authority.

As, however, the evolution of Gorbachev’s ideas and ambition led him to dismantle these pillars of the system, he undermined his own power base. He ran the risk, especially from 1989 onwards, of being overthrown by the leaders of Soviet institutions who felt their own power ebbing away. It required great political finesse, as well as skillful use of his remaining powers, to stave off a hard-line attempted coup until as late in the day as August 1991.

Gorbachev dispensed with one Soviet shibboleth after another. His emphasis on “all-human” interests and values—avoiding nuclear war and halting the trend towards ecological catastrophe prominent among them—was one of many departures from past Soviet doctrine. For Gorbachev, these interests, common to all humanity, transcended class and national interests. The “New Thinking” Gorbachev embraced had its most eloquent expression in a remarkable speech he gave at the United Nations in New York on December 7, 1988. It should have signaled the end of the Cold War in its ideological dimension. Shultz recognized it as such, but he was concerned that the incoming Bush administration was slow to catch on.

Abandoning the central tenets of past Soviet doctrine and, with an idealism verging on the utopian, Gorbachev called in that speech for a “demilitarization of international relations” and for humanity to seek consensus on “a new world order.” He emphasized that any new order must not be “at the expense of the rights and freedoms of the individual or of nations or at the expense of the natural world.” The people of every country, he declared, had the right to choose for themselves their political and economic system.

Over the following 12 months, in 1989, the peoples of Eastern Europe took Gorbachev at his word, and in the Soviet Union itself, contested elections were held for a new legislature with real powers. Ultimately the new political pluralism contributed to the disintegration of the USSR rather than fulfilling Gorbachev’s desire to move from a pseudo-federal state to genuine federation, which he sought to achieve in a lengthy process of negotiation with the Union’s constituent republics.

Many older Russians today blame Gorbachev both for the loss of the Soviet system, from which distance has lent enchantment to the view, and the breakup of the Soviet state, though the latter he strove to prevent, while not reverting to repression. Still less justly, Gorbachev is reproached for the difficulties the older generation have experienced over the past three decades, even though he has wielded no power in Russia since December 1991.

There is a minority, however, of his fellow-citizens who still hold Gorbachev in high esteem and who appreciate his decisive role in ending one-party dictatorship, censorship and doublethink, and in bequeathing them a far freer country than the one he inherited. It is a shame that his 90th birthday comes too soon for that minority to become a majority, but future generations of Russians will surely recognize the magnitude of his achievements and honor the man who broke with an authoritarian and totalitarian past and did more than any other to end the Cold War.