The recent wave of pro-Palestinian protests on college campuses came on suddenly and shocked people across the nation. But the political tactics underlying some of the demonstrations were the result of months of training, planning and encouragement by longtime activists and left-wing groups. At Columbia University, in the weeks and months before police took down encampments at the New York City campus and removed demonstrators occupying an academic building, student organizers began consulting with groups such as the National Students for Justice in Palestine, veterans of campus protests and former Black Panthers. They researched past protests over Columbia’s expansion into...