On the early evening of Thursday, June 16, 1966, when the marchers arrived in Greenwood, Mississippi, and tried to set up camp at Stone Street Negro Elementary School, Carmichael was arrested for trespassing on public property. Carmichael was held for several hours and then rejoined the marchers at a local park where they had set up camp and were beginning a night-time rally. According to civil rights historian David J. Garrow's Pulitzer-Prize-winning Bearing the Cross (page 481), an angry Carmichael took the speaker's platform and delivered his famous "Black Power" speech. King, who had flown to Chicago on Wednesday to help organize the open housing marches, returned to Mississippi on Friday to find that the civil rights movements' internal divisions between the old guard and new guard had gone public. SNCC's "Black Power" slogan was now competing with SCLC's "Freedom Now" slogan.
In Canton, Mississippi the march was attacked and tear-gassed by the Mississippi State Police joined by other police agencies. Several marchers were wounded, one severely. Human Rights Medical Committee members conducted a house-to-house search that night looking for wounded marchers. The nuns of the Catholic school extended their help and hospitality to the marchers, especially to the wounded.
When the march stopped at Tougaloo College before entering Jackson, it was entertained by James Brown and other musicians.
By June 26, when the march entered Jackson, it was estimated to be 15,000 strong. Its passage was warmly welcomed in the black neighborhoods and by some whites. However, many whites jeered and threatened the marchers; others simply stayed indoors.
After hospital treatment Meredith rejoined the March Against fear on June 25, 1966. The following day, the march arrived in Jackson.