The group with one of the strongest claims to the title of world’s first brass band is the Stalybridge Old Band, formed in Manchester in 1809. Soon renamed the New Band, they rehearsed under the baton of Thomas Avison in a cellar behind the Golden Fleece inn. In 1819, its members became involved in one of the defining political actions of the Romantic period, engaged to play at the event that became known as the “Peterloo Massacre”.
"fierce intoxicating tones/ Of trumpets ..." (John Keats)
"The cry went up among the Yeomanry ... Have at their flags!" (Peterloo eyewitness account)
As for Stalybridge Old Band, there's some uncertainty whether the players made it to St Peter's Fields. It's likely that the authorities, having got wind of their planned involvement, detained them at a nearby pub.
Over 11,000 arrests made during the Miners' Strike
I spent this weekend up in Manchester supporting Aberystwyth Youth Band at the National Youth Brass Band Championships. The contest was held at the Royal Northern College of Music, less than a mile away from the site of the Peterloo Massacre.