“The reason the morale of the police department of the city of New York is so low,” Rudolph Giuliani thundered outside City Hall, “is one reason, and one reason alone: David Dinkins!”

In the early 1990s, Dinkins, New York City’s first black mayor, was short on allies and long on problems. The local economy was fragile. Violent crime had yet to noticeably ebb, with more than two thousand people murdered in the five boroughs every year. Racial divisions were stark.

Rudy Giuliani was eager to pile on.