The Cambodian Campaign initiated by U.S. and South Vietnamese forces aimed at disrupting North Vietnamese supply lines and bases located in Cambodia. This military operation was justified by the Nixon administration as a necessary measure to support the South Vietnamese government and combat the spread of communism in the region. However, it quickly ignited widespread protests across America, particularly on university campuses where students had been actively involved in the anti-war movement. Activists argued that the invasion violated Cambodian neutrality and escalated U.S. involvement in the Vietnam War, which was already causing widespread casualties and social unrest back home.

Major protests erupted in various cities, with tens of thousands participating in demonstrations in New York, Washington D.C., and among other locations. College campuses became hotbeds for activism, notably at Kent State University, where hostility between anti-war protesters and law enforcement intensified. Activists organized teach-ins, rallies, and marches to express their opposition, and messages of peace and withdrawal resonated deeply within a divided American society. The protests highlighted the growing rift between the government’s military strategies and the public's increasing demand for peace and normalcy.

The tensions escalated rapidly, culminating in violent clashes, especially at universities where tensions between students and law enforcement surged. This unrest was not just an isolated incident but part of a larger wave of protests that characterized the late 1960s and early 1970s; the anti-war movement was a significant aspect of political expression during this era. The day is often seen as a catalyst for further protests and a monumental shift in public opinion regarding U.S. military intervention in Vietnam and Cambodia.