The Fenian's were a group of Irish Catholics in the united states. The Fenian's were enemies with the British because they felt that in Europe the British treated them poorly. The Fenian's wore green and carried a green flag with the letters IRA. One of the most famous battles between the Fenian's and the British took place in 1866 at ridge way near Niagara.
Between 1847 and 1861 more than 2 million Irish crossed the Atlantic ocean into North America, especially into the United States, this was part of the great migration.
The people of British North America feared that the Fenian's would invade, a few invasions
occurred. In 1866 at Pigeon hill , from Vermont, the Fenian's attacked Canada East but found no soldiers when they advanced 10km. When the Fenian's heard that colonial troops were on the way to intercept them they retreated. 16 Fenian troops were captured and the rest were disarmed and sent back into Vermont.