College students face a tough close to the school year. The Atlantic, with its characteristic sense of history recently called the coronavirus pandemic “the single most disruptive event in American higher education in at least a half century.” It is worth looking back fifty years in university history to the last time school was out.

Starting as early as 1964, student protest swelled throughout the decade; mostly fueled by Vietnam, mostly at elite campuses and big state schools. On April 30, 1970, Richard Nixon announced he was sending troops into neutral Cambodia and things escalated. Historian Ira Gitlin estimated that about half of America’s college students participated in protest at some point that spring.

The fuse was Cambodia, the dynamite Kent State—my undergraduate alma mater. On May 4, 1970, the Ohio National Guard killed four students during antiwar protests at a school mostly attended by middle- and working-class students—not the type supposed to make trouble. There were about 2,500 colleges and universities in the United States at the time. About half of them exploded in protest. Students went on strike at about a third. On May 14, trigger-happy police killed two more students at Jackson State in Mississippi.

By then administrators had closed a large number of schools, at least temporarily. While some students kept protesting, others mobilized through organizations like Young Americans for Freedom to reopen campuses.

But as political cartoonist Herblock observed, it was “The End of School,” not only for six students from Mississippi and Ohio but for thousands more. About 75 institutions closed for the remainder of the academic year. There were no virtual classrooms or ceremonies. Most schools allowed students to get a pass/fail grade or take an incomplete. Graduates got their diplomas in the mail.