To enforce desegregation.
Granted I was in 3rd or 4th grade at the time but it was in our Weekly Reader and seemed a big deal at the time.
On September 23, President Eisenhower issued Executive Order 10730, which put the Arkansas National Guard under federal authority, and sent 1,000 U.S. Army troops from the 101st Airborne Division to Little Rock, to maintain order as Central High School desegregated.
Our enemies are gloating over this incident and using it everywhere to misrepresent our nation, said Eisenhower, in a televised address he gave at the White House the day after he enforced his executive order. Mob rule cannot be allowed to override the decisions of the courts.
Eisenhower was boxed into a corner and reached a point where he had to show the power of the federal government and chop off continued insurrection of southern segregationists, says Dolores Barclay, an adjunct professor at Columbia Journalism School and administrative manager of the Lipman Center for Journalism and Civil and Human Rights. His decision was decidedly politicalto maintain federal powerand to ensure that Brown was enforced.
The use of Federal military is not unprecedented inside of our borders.
https://www.history.com/news/little-rock-nine-brown-v-board-eisenhower-101-airborne