Why did the national guard have to visit the university of mississippi in 1962?

The national guard visited the university of Mississippi in 1962 due to the riot which started on 30-09-1962 by segregationist from the south, in which they had fracas with the Federal forces stationed at the University of Mississippi campus in Oxford, the reason behind the riot and fracas was because the segregationist does not want the enrollment of the first ever Afro - American in the university, therefore president John F. Kennedy sent federal marshals to the university to curtail the situation.