In 1866–67 a drill-shed was erected in East Oro by the Oro Company, 35th Battalion the Simcoe Foresters. At this time when the Fenian raids were alarming the country, eight company drill-sheds were built in Simcoe County, the county paying $390 and the government $250 for each. The company was manned by pioneer men of Oro. Local Wm.E. O'Brien of Shanty Bay became Lieutenant Colonel of the Battalion in 1882. This East Oro drill-shed served Oro Company until the start of the 20th century and was dismantled around 1918.