On the night after Martin Luther King Jr. was assassinated in 1968, James Brown’s improvised speech onstage at the Boston Garden (broadcast live on local TV station WGBH, with encore presentations immediately thereafter) helped calm a grieving, angry community engaged in nationwide spates of rioting.

“We are black! Don’t make us all look bad!” Brown insisted to a group of kids who’d charged the stage in defiance of the cops. “Let me finish the show … You’re not being fair to yourself or me or your race. Now I asked the police to step back because I thought I could get some respect from my own people. It don’t make sense. Are we together or are we ain’t?”

“Even though I was going to take a financial bath, I knew I had to go on and keep the peace,” Brown recalled in a 2005 memoir. “There are some things more important than money.”

Boston Mayor Kevin White had considered cancelling the show but feared that move, too, might prompt a violent response. A young African American city councilman, Tom Atkins, advanced the idea of a free broadcast of the show, which would keep people at home, glued to their TVs.

The episode came to be known, in some circles, as “the night James Brown saved Boston.” What’s more, officials in other imperiled cities, hoping to quell unrest after MLK’s murder, reached out to the Hardest Working Man in Show Business for assistance; he became, for that brief time, a roving ambassador of urban peace.

A documentary about this chapter, The Night James Brown Saved Boston, was released in 2008.