Fort Erie Occupied
The Fenians first invasion into British North America occurred in April 1866, when the faction led by John O'Mahony attacked Campobello Island in New Brunswick. Although O'Mahoney advocated for a revolution in Ireland instead of British North America, he feared he was losing support to William Roberts. He decided to take the initiative and plan an attack. But their weapons were taken by American authorities, and the Royal Navy and New Brunswick militia responded promptly to the threat. It was an embarassing failure for the Fenians.
After this loss, William Roberts felt a sense of urgency to attack again before support for the group declined further. This was not what the Canadian government expected and they became complacent about the Fenian threat, believing that the danger was over. When a group of about 1000 Fenians crossed the Niagara River at night on May 31, 1866, the Canadians were caught by surprise.
A newspaper dated June 2, 1866, reports on this event, noting in the headline that "the old demolished Fort Erie in their possession". It follows that "we announced yesterday that Fort Erie was in possession of a band of Fenians who crossed from Buffalo during Thursday night and took possession. Fort Erie is an old demolished fort incapable of being rendered of any strength, and was not defended by any troops". The paper further reports that the Fenians were in possession of Taylor's Heights, just below Fort Erie, and that they had opened a recruiting office at Fort Erie.
The Fenians seized control of Fort Erie's railway and telegraph terminals, arrested the town council and customs officials, and forced bakeries and hotels to provide them with food. They took horses and tools, building trenches and fortifications. By the end of the day, the Fenians had control of the Niagara frontier from Black Creek to Fort Erie.