Normans invaded Gwynedd. Rhuddlan's strategic position ensured that it was fought over by the Princes of Gwynedd and the Earls of Chester, with Gruffydd ap Llywelyn, who had been driven out by Harold Godwinson, re-taking the town. The remains of a Norman castle at Twthill, built in 1086, is just to the south of the current castle; it was built by Robert of Rhuddlan, a supporter of King William I of England. In July 1277, at the outbreak of the Welsh Wars, Edward I left Chester and established an advance base at Flint, where building work immediately began on Flint Castle. With naval assistance from 25 ships of the Cinque Ports fleet, the army pushed along the coast. By August Edward had moved his forces on to Rhuddlan, which, as was his custom, he was able to supply by river. Three months later the town was ceded to the English Crown following the Treaty of Aberconwy between Llywelyn ap Gruffudd and Edward I. Work on Rhuddlan Castle began immediately under the control of Master Bertram, a Gascon engineer, but construction was soon handed over to Savoyard master mason, James of St George who remained in charge until labour ceased in 1282. Besieged by the Welsh during the rebellion of 1282, until relieved by an English force led by future Amadeus V, Count of Savoy. Edward I also created a new borough, north of his castle, away from the pre-existing Norman town and Dominican Friary. The 13th-century street layout can still be seen in the modern town. The borough, like at Flint, was defended with a pair of ditch-separated earthworks and a timber palisade. Rhuddlan Castle became a part of Edward's Ring of Iron fortifications. Elizabeth, the eighth daughter of Edward I, was born at Rhuddlan in 1282, the same year work at the castle was completed. Two years later the Statute of Rhuddlan was signed at the castle following the defeat of Llewellyn the Last, who had attacked the castle unsuccessfully. It ceded all the lands of the former Welsh Princes to the English Crown and introduced English common law. Edward I could now appoint Royal officials such as sheriffs, constables, and bailiffs to collect taxes and enforce English law throughout Wales. Following Rhuddlan, the counties of north western North Wales were placed under the control of the Justiciar of North Wales. Although the statute brought in English legislation, Welsh