In 1170, during the Norman invasion of Ireland, Strongbow and Dermot MacMurrough successfully laid siege to Dublin by following a high route through the Wicklow Mountains, avoiding the defences along the normal route to the west of the mountains. The Norman invasion displaced two important Gaelic clans from Kildare, the O'Byrnes and the O'Tooles, who moved into the Wicklow Mountains, the O'Byrnes in the east and the O'Tooles in the west. From their mountain strongholds both families conducted a persistent campaign of harassment against the invaders and the Wicklow Mountains became known as the terra guerre (land of war), as opposed to the terra pacis (land of peace) of the settled lowlands.