The famous Newport Rising, which occurred in Monmouthshire in 1839, was an ugly offshoot of the Chartist movement demanding the vote for working-class men.
Though action was long planned, the revolt quickly escalated when key Welsh Chartists were detained in a Newport hotel. Hearing this, an armed mob of perhaps 5,000 went to liberate them, and opened fire on the local yeomanry.
The soldiers retaliated, killing around 20, and the mob soon fled in panic. The ringleaders were sentenced to death, but this was later commuted to transportation.
Some contemporary conspiracy theorists feared that this uprising was just the beginning of a sinister Russian invasion plot, and that the whole nation would soon be under attack.