Kent State. As soon as they shot some whiteys they stopped shooting anybody.
Kent State marked the END of an increasingly violent and pretense ridden left wing "student" revolution. Hot lead ended the pretense and the rebellion. No ROTC buildings have been burned since and no spoiled Marxist campus Cong have "marched on the guard" since. The burning of the Kent State ROTC building was a fatal blunder of the left.
The public massively approved and Nixon swept McGovern, the campus Cong hero, carrying 49 states two years later. The other official with backbone was "moderate" Ohio Republican governor Jim Rhodes.