After having received a grant of Ulster from King Henry II of England, Norman Knight John de Courcy set out from Dublin in early 1177 to take possession of it. He marched north with a force of 20 knights and 300 men and reached Downpatrick four days later. Downpatrick was an open ecclesiastical town of the old type, and the invaders rode in and surprised it in the small hours of 2 February. De Courcy attacked the fortress and administrative centre of Rath Celtair (the Mound of Down), defeating and driving off Rory MacDonlevy (Ruaidhri Mac Duinnshleibhe), King of the "Dál Fiatach" and Ulster (Ulaid).