This type of structure is somewhat common in Ireland, but the only Scottish examples are those at Brechin, Abernethy in Perthshire, and Egilshay in the Orkneys.
William the Conqueror answered this attack by marching into Scotland in 1072, whereupon Malcolm made peace with the English king at Abernethy and "was his man."
Besides the dozen forts on the wall, one or two outposts may have been held at Ardoch and Abernethy along the natural route which runs by Stirling and Perth to the lowlands of the east coast.
At the same time the Roman forts at Ardoch, north of Dunblane, Carpow near Abernethy, and perhaps one or two more, were occupied.
In 1072 William marched north and took a disputed homage of Malcolm at Abernethy, receiving as hostage the king's eldest son (by his first wife, Ingebiorge), named Duncan.