In 1866, the relationship between the British and American governments were strained, as a result the British rushed troops to Canada to prepare for an American invasion. However, tensions were also high between Britain and Ireland. Enter the Fenian Brotherhood, a group of Roman Catholic Irish Nationals who were living in the United States. This group of men wanted to free their Catholic brothers controlled by a Protestant English government in Ireland. A plan was put in place for the Fenians to invade Canada and use it as a pawn to trade for a free Ireland.
The Fenian threat was considered a real and present danger to the settlers living in Canada. In the Protestant majority County of Dufferin, rumors floated freely of an impending Catholic invasion. In 1864, rumors made their way to the Northern part of the County that the Fenians had crossed the border. According to the talk of the town, the Fenians had made it to Mono and were indiscriminately attacking Protestants and destroying the Presbyterian Church and Orange Hall. The rumor was proven to be a hoax only after people had flocked together and taken up arms for protection. Although it was a hoax, the fear of a Fenian Invasion was a real fear to the Protestants in Dufferin County.
Given the ever-present threat of a Fenian invasion, and the tensions increasing between Britain and America, and men were asked to join the local Militia Units created specifically to combat this threat. in 1866. Orangeville and Amaranth drafted two battalions of men to be trained and ready in the event of an invasion.
In June 1866, news broke that the Fenians were planning on crossing the border at Fort Erie. With this news, thousands of men took up arms and headed for the woods surrounding the Fort. All the while rumors were spreading around Dufferin County and people believed that the Fenians had taken nearby regions such as Adjala and Mono Mills. The Orangeville militia unit was sent to Toronto for three weeks for training exercises and waiting for the Fenians to attack. There were several false alarms while the battalion was training in Toronto, but no Fenians were to be seen.
In 1867, a uniformed cadet company was placed under the command of Captain Orange Lawrence and Drill Seargent Thomas Campbell. The Fenian threat continued to plague the minds of many Canadians, issuing mostly unsuccessful raids on Canada between 1866 and 1871.