When you think of American student peace activism, you probably don’t think of the late 1950s and early 1960s. But you probably should, and today is the fiftieth anniversary of one huge reason why.

For most of the 1950s the United States was regularly testing nuclear weapons above ground, and in ways that today seem almost unimaginably reckless. Dozens of atomic bombs were set off in Nevada, barely sixty miles from Las Vegas. Other tests were conducted near populated islands in the Pacific, including one that led to large-scale evacuations after the bomb turned out to be nearly twice as powerful as planned. In 1958 the US detonated a nuclear weapon in space, and planned to use several more to carve out an artificial harbor in northern Alaska to use as a transit point for oil and coal shipments from the area.

For student activists of the age, nuclear weapons represented everything that was wrong about modern militarism — the threat of global war, the targeting of civilians, the recklessness of US-Soviet brinksmanship, ties between the military and corporations. In 1957 students created a campus affiliate of the new National Committee for a Sane Nuclear Policy (SANE), and two years later, in 1959, they established two independent student antiwar groups, the Student Peace Union and the College Peace Union.

This campus organizing of the late 1950s was limited in comparison with the protests that came later, but it helped to build toward what followed — Student SANE, SPU , and CPU were organizing on campuses before SDS or SNCC were even conceived. (Student SANE was set adrift by its parent group in 1960 after SANE tried to purge students who refused to support a strict anti-Soviet political line. Many Student SANE members migrated to the SPU after that. CPU merged with SPU that same year, taking the latter’s name.)

The United States, the Soviet Union, and the United Kingdom, then the world’s only nuclear powers, declared a moratorium on nuclear testing in 1958, but the moratorium collapsed after France tested its first bomb in early 1960. The Soviet Union resumed testing that fall, and the United States followed suit the following year.

The resumption of testing prompted a wave of campus protest, with demonstrations held across the country. In February 1961, ten thousand student marched on Washington to urge the US to continue its testing ban. In March 1962, after testing had resumed, hundreds of anti-testing Berkeley students picketed President Kennedy when he spoke on campus. (In a prelude to the Free Speech Movement of 1964 SLATE, the activist campus political party at Berkeley, had been forced to withdraw its formal support for an anti-testing vigil the previous fall when the administration declared that any “action of a social or political nature” by student organizations was prohibited.)

At its height, the Student Peace Union had dozens, perhaps hundreds, of campus chapters, and a paid individual membership roster of four thousand — in 1962 and 1963 it was, as historian Philip Altbach has described it, “the largest radical student organization in the United States.” Campus activists kept up public pressure for a test ban in those years, pressure that helped bring American, British, and Soviet negotiators to the table in 1963. A ban on all atmospheric, underwater, and space-based nuclear testing was agreed to late that summer, and ratified by the United States Senate on September 24, 1963 — fifty years ago today.

The SPU lost focus after the signing of the test ban treaty, as many of its members took their skills and their energy into the civil rights movement, campus organizing, or the growing Students for a Democratic Society. In doing so, they helped to build the student movements of the sixties that followed — without their work and their example, the sixties would not be the sixties we know today.