In 1066 AD everything changed when the Saxon King Harold Godwinson was defeated by William Duke of Normandy. The Normans rapidly established control over England, becoming the aristocratic rulers of the Anglo- Saxons.
Wales remained independent, but William had rewarded his most loyal general with large territories along the border between England and Wales. These were know as the Welsh Marches and the nobles had the authority to keep their own armies – with the primary focus of ensuring the Welsh did not pose a threat.
There was however a quiet migration to the Vale of Glamorgan of people of Irish, Norse and Anglo-Saxon descent from places such as Somerset. The Vale thus became an area of mixed population, with some unsympathetic to the cause of Welsh Independence who were happy to acquiesce to Norman rule when it came.
In 1145 AD Rhys ap Tewdwr, the Prince of Deuheubarth (South West Wales) was at war with the lords of Glamorgan – Iestyn, Einon and Cedrych. Iestyn had made promises to Einon and Cedrych to encourage them to join him against Rhys. However, Rhys, was more powerful than the combined power of the three Lords, so Iestyn co-erced one of the Norman Lords in to join them to defeat Rhys.
With the help of Sir Robert Fitzhammon, Rhys was defeated. Iestyn then reneged on his promises to Einon and Cedrych, who again enlisted the help of Sir Robert. Sir Robert emerged the victor and as a result divided the Kingdom of Glamorgan into manors shared among his knights and followers.
Treoes at this time was known as Goston and was contained within the manor of Corntown, which together with the Manor of Ogmore was ruled by Sir William Londres. Sir William built Ogmore Castle and founded the Benedict Priory at Ewenny.
The Manor of Coity, Newcastle (in Bridgend) and Court Colman was granted to Sir Payne Tuberville.
The manor of Penlline, Llangan and Goston later fell into the hands of Sir Robert De Norris in the early 12th century and it remained with the family until the early 14th century. The manor was run on feudal lines with free and unfree tenant farmers.
In nearby St Mary Hill there were two manors Gelligarn (known historically as Kilticar) and Ruthin.
Gelligarn belonged to Simon De Alweias (the family were later known as the De Haweys). Simon built a motte and bailey castle at Gelligarn to strengthen their hold over the area. These simple fortifications could be erected relatively quickly by the Normans. They consisted of a ditch and a banked circular enclosure, with a timber fort on the highest part. Simon was so harassed by Welsh raids, particularly from nearby Ruthin, that he exchanged his Knights fee for Gelligarn with the Cistercian monks at Neath Abbey. In return Simon received a far safer estate in Littleham in Devon.
The monks of Neath Abbey then established a sizeable Grange on the land, thus forming a buffer between the warring camps. The ruins of the dovecote at the Grange can still be seen.
From the time of the Norman Conquest, roads ran out from Treoes, marking off the open fields from the common land. Moor Mill on Treoes Moors was the corn mill for Penlline, Llangan and Treoes. It is still possible to trace the old road called Heol-y-Millway running from Penlline to Treoes. (David Francis)
Previously known as Goston, Treoes is of great antiquity and is a perfect example of a street or ribbon village dating back to the Middle Ages (D. J. Francis). Given the good agricultural land in the area the Normans established their corn growing manors here, based on the feudal system which was designed to enable a relatively small amount of aristocrats to dominate a large number of peasants. They controlled the law, religion, education, land tenure, coinage, the military and the ownership of weapons.