The deer, named Billy, was mascot of the East Barracks at Carrignagroghera, and his memorial is one of the more quietly peculiar things to survive from a substantial military complex that once occupied a commanding position above the Blackwater River. The internal buildings are entirely gone, but the high enclosing stone wall remains largely intact, and on its inner western face you can still read the ghost marks left by the structures that once leaned against it.

The barracks was built in 1806, on a level plateau overlooking the river and the town of Fermoy roughly 400 metres to the south. By the time the Ordnance Survey mapped it in 1842, the site was a sizeable operation: a rectangular ordnance ground of roughly 200 metres north to south and 250 metres east to west, containing three long ranges of buildings arranged around three sides of an open area, with a guardhouse closing the fourth side. Beyond the northern range lay a separate cavalry barracks and a forage yard. A square graveyard was marked just outside the north-eastern corner. The complex was not alone; another military barracks stood only about 200 metres to the west, and a military hospital was sited approximately 200 metres to the north-north-west, giving some sense of how thoroughly this stretch of north Cork had been organised around a British garrison presence in the early nineteenth century.

The southern entrance on the western wall survives as a cut-stone archway pierced by gun loops, a design closely echoed in the archway on the west barracks across the way. The northern gateway, now blocked, is where Billy's plaque sits. The interior, stripped of every building that once gave it its military purpose, is occupied today by the playing fields and clubhouse of Fermoy GAA club, a transformation that would have been difficult to anticipate when the ordnance ground was first laid out.