Original sentence: During the late 1960s and early 1970s, the university was known internationally for its student activism in opposition to US involvement in the Vietnam war, due mainly to the events of May 4, 1970
Edited sentence: During the late 1960s and early 1970s, the university was known internationally for its student activism in opposition to US involvement in the Vietnam war, due mainly to the  tragic events of May 4, 1970