The fort at Drumbanagher is a substantial thing: a subcircular area roughly 95 metres north to south and 85 metres east to west, ringed by an earthen bank and an outer fosse, which is a defensive ditch, with a narrow original entrance facing east-south-east. Mature deciduous trees now fill the interior, giving it the appearance of a small private wood rather than an ancient fortification. The bank still stands to a height of around three and a half metres on the exterior at the southern side, and the fosse retains a width of approximately ten metres at the top. McCrea's 1793 map of County Monaghan recorded it, which tells us it was already a recognised feature of the landscape by the late eighteenth century, though the enclosure itself is considerably older.

What gives this quiet hilltop an unexpectedly sharp historical edge is a skirmish that took place here, on or around 13 March in the late 1680s, the precise year disputed between 1688, 1689, and 1690. The encounter was between John McKenna and Mathew Anketell, the latter having recently relieved a Protestant population at Glaslough, a few miles to the north. By any measure it was a minor engagement, but both men paid for it with their lives: Anketell died on the field, and McKenna died later in captivity. The site did not give up physical evidence of that day without some persuasion. A metal-detection survey conducted by Dr. Siobhán McDermott as part of doctoral research at NUI Galway identified two clusters of signals consistent with lead shot, one outside the eastern edge of the enclosure, recorded as McKenna's position, and a second on a small north-south ridge approximately 200 metres to the east. The scatter of shot across two distinct locations offers a faint material trace of how the fighting moved across the ground.