LITTLE ROCK, Ark., Oct. 3--Federalized National Guardsmen today broke up a menacing throng of 75 white students who walked out of integrated Central High School.

The demonstrators had hoped to pull out with them most of the school's 2,000 white students in a forceful protest against Negroes in their classrooms. But ring-leaders admitted the demonstration was a flop.

A straw-filled dummy used to hang a Negro in effigy was set afire. The demonstrators shrieked and shouted in near hysteria but gave way before National Guardsmen.

Within 30 minutes the streets in front of the school were deserted and quiet. Barricades were restored in the area for the first time since last week.

Eisenhower Criticizes Faubus

WASHINGTON, Oct. 3--With the question of withdrawal of federal troops from Little Rock still unsolved, President Eisenhower at his news conference today said he believes Faubus is "mistaken in what he is doing, and is doing a disservice to the city and to his state." He reiterated his demand for "satisfactory and unequivocal assurances" that order would be maintained.

In Little Rock, Faubus told a news conference he had given the President "unequivocal assurances to maintain order" but made no direct reply to Eisenhower's remarks.