Randy Forsberg, who died this month at age 64, left a remarkable legacy: She helped end the Cold War, the most costly and dangerous confrontation in world history. This singular achievement was not hers alone, of course, but she spurred the massive social movement in the United States and Europe that convinced the superpowers - the United States and the Soviet Union - that they had to stand down from their nuclear rivalry.In 1980, she invented the call to freeze the nuclear arms race, and this simple but compelling idea - essentially, a moratorium on new nuclear weapons as a prelude to gradual disarmament - became the rallying cry for millions of people sickened by the rush to develop and deploy new nuclear weapons and missiles, space weapons, stealth bombers, and all the other expensive, provocative gadgets of the arms industry.

The nuclear freeze idea, and the citizens' campaign that galvanized the world to embrace it, gradually altered the opinions of the public and then the policy makers in the United States and elsewhere. In America, the quickly rising popularity of the freeze collided with the equal popularity of President Ronald Reagan, who accelerated the arms buildup in the early 1980s. But the freeze movement changed Reagan's own calculations, driving him toward arms control negotiations and softer rhetoric toward the USSR by 1984.

When Mikhail Gorbachev became the Soviet premier in 1985, the possibility of dramatic action to reduce the nuclear danger suddenly seemed feasible. Gorbachev was influenced by the freeze idea and other arms control proposals. When he began a series of unilateral steps to demonstrate his willingness to end the nuclear rivalry, most policy and political experts in the United States were skeptical, and rejected his overtures.

But the public was increasingly adamant about ending the nuclear arms race, and they responded with cautious but unmistakable support for such disarmament measures. Reagan, a master politician, also recognized this opportunity. Buffeted by the Iran-Contra scandal that was revealed in November 1986, he immediately moved to engage Gorbachev and the relatively radical ideas for stopping the nuclear rivalry.

The first great test of this new bilateral cooperation was the Euromissiles treaty in 1987, which eliminated the new missiles NATO was installing in Europe and those the USSR had aimed at Europe. Initially opposed by the defense intelligentsia in Washington and much of the Democratic leadership in the Congress, the overwhelming popularity of this measure altered the elites' resistance. Other arms reduction measures followed.

This sudden turnaround in US politics could be explained by one factor above all others - the public had become convinced, by the freeze movement particularly, that something substantial had to be done, and soon, to end the nuclear peril. The politicians, news media, and experts followed suit. A citizens' movement in Europe pressed this upon their governments, and this even spilled over to affect the Soviet establishment.

It was an extraordinary victory for civil society, and Randy Forsberg was at its root. She wrote and spoke tirelessly on behalf of the freeze and similar proposals. She engaged policy makers, national security analysts, and reporters. She helped build an infrastructure of new think tanks and activist organizations. She spread the word to Europe and the Soviet Union. And she continued to agitate for nuclear disarmament after the Cold War (and the Soviet Union) ended.

Above all, her exemplary life is a tribute to the power of an individual's capacity to change history. Her combination of knowledge, inventiveness, and persistence is itself a rarity. But Randy Forsberg proved it could be done, a glorious paragon of the better angels of our nature.

John Tirman is executive director and principal research scientist at the MIT Center for International Studies.

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