In early March 1967, a Columbia University SDS activist named Bob Feldman reportedly discovered documents in the International Law Library detailing Columbia's institutional affiliation with the Institute for Defense Analyses (IDA), a think-tank affiliated with the US Department of Defense. The nature of the association had not been, to that point, publicly announced by the University. Columbia University is a private university in the Morningside Heights neighborhood of Manhattan, New York City. ... The Institute for Defense Analyses (IDA) is a non-profit corporation that administers three federally funded research and development centers to assist the United States Government in addressing important national security issues, particularly those requiring scientific and technical expertise. ... A think tank is a research institute or other organization providing advice and ideas on problems of policy, commerce, and military interest, and are often associated with military laboratories, corporations, academia, or other institutions. ... The United States Department of Defense, abbreviated DoD or DOD and sometimes called the Defense Department, is a civilian Cabinet organization of the United States government. ...

The discovery of these documents touched off student protests across much of the social science sections of the campus. For several days, students took over administration buildings, occupied classrooms, and demonstrated against Columbia University's involvement with the IDA, a new gym construction project in Harlem's Morningside Park and for amnesty for all participants in the demonstrations. The protests came to a conclusion when the NYPD violently quashed the demonstrations. Many students were injured and taken to hospitals, while over 750 protesters were arrested. The New York City Police Department (NYPD), the largest police department in the United States, has primary responsibility for law enforcement and investigation within the five boroughs of New York City. ...

Columbia ended up scrapping the plans for the controversial gym and built a subterranean physical fitness center under the north end of campus instead. At least 30 Columbia students were suspended by the administration.