Two 'accidents' sparked the clashes. In the first, the police received a bogus emergency call about an armed robbery at Harlem's Mosque No 7, run by the Nation of Islam, which in turn is run by the demagogic black minister Louis Farrakhan. There was no robbery, just a group of black Muslims in a prayer session. The black Muslims objected to the police intrusion and a fight broke out which, fortunately and remarkably, was restricted to fisticuffs. The brawlers spilt out on to the pavement and eight policemen were injured, plus an unknown number of people from the mosque.
True to his image as a tough law-and-order man, the mayor backed the police action and was generally praised for doing so among the constituency that elected him: middle-class whites. Among blacks he was severely criticised. They called him a 'fascist' and 'despicable' for sending police into such a 'sensitive' place.
No arrests were made because the mosque leaders promised to produce the names of those who were in the brawl, but they did not. So the police started their own inquiry and on Wednesday arrested their first suspect. More arrests are promised.
Meanwhile, the mayor's new police chief, William Bratton, who came from Boston vowing to clean up New York streets, refused to meet the city's most vocal black minister, the Rev Al Sharpton, to discuss the matter. The rebuff was taken by black leaders as Giuliani-inspired because the mayor had also refused to meet Mr Sharpton.
In fact, the mayor had laid down a rule about meeting ethnic leaders of any hue. He is prepared to reach out to them only, he said, 'if they will discipline themselves in the way they speak'. Both whites and blacks saw this as a condescending, even chilling, remark that did not help race relations in the city - especially as he won only 5 per cent of the black vote in last November's mayoral election.
Then came the second 'mistake'. In a case unrelated to the mosque incident the 17-year-old son of a black Muslim cleric was shot dead by a black policeman. Police had been called to a private house where the youth was accused of selling drugs. As they approached, the youth 'reached into his waistband' as though for a gun, according to the police. The police said they found 24 crack vials in the house.
Fortunately for the mayor the clashes were followed immediately by a weekend of ethnic healing during the remembrance of Martin Luther King's birthday. The mayor was able to go before black audiences and, over the din of the hecklers, try to convince the suspicious black community of his fairness. With poise and patience he told them, 'I have the same love, respect and caring for the African-American community as I do for all the communities of our city. Give me a chance.' Whether they will or not depends on the mayor's next steps, and also on a period of calm in the city's black neighbourhoods.