BRUNSWICK, Ga. — A 26-year-old black man stood on the steps of the old brick courthouse on Friday and decried the shooting death of another black man who would have turned 26 that day had he lived to see it. “That could have easily been me,” he said.

There was anger and anguish and cries of “No justice, no peace!” stirred by the shooting death of Ahmaud Arbery in February. But there was also an interracial crowd, strong words from the white Glynn County sheriff, Neal Jump, and a sense of honoring a history that added an unexpected note to an all-too-familiar drama of a young black man being gunned down under troubling circumstances.

Looming over the grim vigil was also Brunswick’s legacy as a “model Southern city,” its reputation shaped by national attention and praise decades ago for the way black and white leaders had worked together to integrate with far less of the acrimony that had boiled over in desegregation efforts elsewhere.

As outrage over Mr. Arbery’s case has swept through Brunswick and beyond it, amplified by a graphic video capturing his fatal encounter with two white men, activists and leaders have strained to maintain that legacy in the face of a potentially explosive situation.