Their original territory comprised the southern part of the present County Kildare but they were driven from it during the Anglo Norman invasion and settled in the mountains of what is now County Wicklow around Glendalough.
Here, with their kinsmen, the O'Byrnes they were noted for their resistance to English domination for four centuries. Throughout their history the family were famous as soldiers, from fighting the English in the glens of Wicklow to serving in the armies of other European countries in the 18th century. Sergeant O'Toole of the 9th Queens Royal Lancers of the British Army was awarded a Victoria Cross for conspicuous bravery in the Zulu War on July 3rd, 1879.
A branch of the O'Tooles are also settled in counties Galway and Mayo.