The president of the United States went on television to announce that the ruler of one rogue state would not be allowed to defy the will of the world. He hoped for peace, but if necessary US forces would go in with overwhelming power. He talked about his "obligation under the constitution and the statutes of the United States".

It was not George W Bush but John F Kennedy, 40 years ago today, on September 30 1962, and the state was one of the not very united ones, Mississippi, then engaged in one of the last big spasms of overt resistance to the principles that might have been established by the civil war a century earlier. It was a crucial moment in the struggle to end segregation in the US.

It was sparked by James Meredith's attempt to become the first black student to enrol at the University of Mississippi - "Ole Miss". The state governor himself, Ross Barnett, stood in the doorway to prevent him registering.

Kennedy sent 750 federal marshals to the university town of Oxford to escort Meredith inside, but they were overwhelmed by furious whites. Two people were killed and dozens injured in the ensuing riot: the modern United States may never have been so close to a full-scale public uprising. It made Mississippi a worldwide byword for intolerance and racism, an image the state has not entirely eradicated.

The president, alarmed by intelligence reports that armed segregationists were heading to Oxford from all over the South and beyond, ordered an overwhelming display of force. Meredith was escorted to classes next morning by marshals, backed by a squad of soldiers outside and 23,000 more camped around the city: the battle was won. "It was a sheer miracle that scores, if not hundreds, of Americans were not slaughtered that night," in the view of William Doyle, author of An American Insurrection, an account of the crisis.

Social segregation

This week some of the principals will return to Oxford to consider whether the war was won as well. These days 13% of the students at Ole Miss are black, and James Meredith's own son has just, quietly, obtained a doctorate in business administration. But Mary Margaret Miller of the university newspaper, the Daily Mississippian, says the problems have not entirely gone away. "Although Ole Miss has been legally integrated, it remains socially segregated."
James Meredith will be among those taking part in the anniversary conference, though his contribution may be unpredictable. He is 69 now, and rather unwell. He lives in the state capital, Jackson, where he runs a car-hire business aimed at poor families, but he has never become a poster boy for the civil rights movement. Four years after the riots, he even endorsed Governor Barnett's campaign for re-election.

The role of President Kennedy was not conventionally heroic either: he tried to persuade black activists to rein back their demands, and badly underestimated the gravity of the Oxford crisis. Once it was over, though, the segregationists' power was weakened, and the path clearer for the civil rights legislation passed under Kennedy's successor, Lyndon Johnson.

The Guardian's correspondent in Oxford, Bill Weatherby, was among those beaten up on the streets and a French reporter was one of those killed: journalists were considered legitimate targets.

Yet, in one of those Southern paradoxes that still abound, one of the angry whites, a pool hall owner, let Weatherby sleep on a billiard table, the nearest thing the town had to an available bed. "Ole Miss will certainly never be the same again," Weatherby wrote. "Nor perhaps, under the surface, does it want to be."