The Civil Survey of 1654 to 1656, a detailed land inventory carried out in the aftermath of the Cromwellian conquest to establish ownership and value across Ireland, names this spot as "the foord of Ballavullin," the older anglicised spelling of what is now Ballywillin. The ford sat on the eastern edge of the medieval barony of Granard, a territorial division whose centre at Granard town was dominated by one of the largest Anglo-Norman mottes in Ireland. A ford, simply a shallow river crossing passable on foot or horseback, was often the determining factor in where roads ran and where settlement clustered, and this one appears to have served exactly that function at a county boundary where Longford meets Cavan. The present bridge over the river may have been built directly on the site of that earlier crossing, continuing a line of movement that predates any modern road by several centuries.