American fenians led by general john oneill invade canada and capture fort erie.

The Fenian raids were attacks by members of the Fenian Brotherhood based in the United States, on British army forts, customs posts and other targets in Canada in order to bring pressure on Britain to withdraw from Ireland, between 1866 and 1871. The raids were successfully repelled by British forces and local militias. They divided many Irish-Canadians, many of whom were torn between loyalty to their new home and sympathy for the aims of the Fenians. A lot of the Irish, particularly the Protestants, were fiercely loyal to Britain and fought the Fenians. While the U.S. authorities arrested the men and confiscated their arms afterwards, many in government had turned a blind eye to the preparations for the invasion, angered at British support for the Confederacy during the American Civil War. There were five Fenian raids to note.

Fenian commander John ONeill and an Irish-American force crossed the Niagara River and skirmished with a brigade of Canadian militia near Ridgeway, Canada West (now Ontario) on June 01, 1866. Several hundred other Fenians (Canadian sources claim up to 3,000) remained in the US, prevented from crossing the river by the arrival of the US Navys side-wheeler gunboat USS Michigan.

The Battle of Fort Erie was a bloody skirmish immediately following the Battle of Ridgeway on June 02, 1866, in Canada. The victorious Fenian army, withdrawing towards the United States, met and defeated a small force of Canadian militia at Fort Erie.