The first settlement which led to the foundation of modern Newport appears to have been on the top of Stow Hill, where by tradition St Gwynllyw (St Woolos) established a church in the fifth or sixth century. It is possible that the large hillfort on the other end of the ridge leading from Stow Hill, now called The Gaer or Tredegar Camp, could have been used as a stronghold for the sub-kingdom (cantref) of Gwynllŵg. The cantref’s boundaries appear to have stretched from the mouth of the River Usk in the east, to Rumney in the west, and from the sea to the border of the later Breconshire.
There is little evidence of the early history of Gwynllŵg. In the sixth century it was part of the kingdom of Glywysing (later to known as Morgannŵg). By the tenth century it appears to have been a separate kingdom, lying between the kingdom of Gwent in the east and the kingdom of Morgannŵg in the west, but by the time of the Norman Conquest it had re-united with Morgannŵg. Later, a division or commote of Gwynllŵg, consisting of the area next to the coast, became known as Wentloog (a corruption of Gwynllŵg).
The name Stow is an Old English word, usually interpreted as a ‘place of assembly’ or ‘holy place’, and there is some evidence of a Saxon presence in the area. The Brut Y Tywysogion records that in about 971 AD ‘Edgar, king of the Saxons collected a very great fleet at Caerleon upon Usk’  . In addition the Anglo-Saxon Chronicle records that around 1049 AD Viking ships from Ireland raided up the River Usk, and that, aided by Gruffydd, the Welsh King, they defeated the Saxon bishop Ealdred.  Another reference, in the Vita Gundlei (Life of St Gwynllyw) refers to Saxon merchants having to pay tolls at the mouth of the Usk and to a raid by Harold Godwinson in 1063, after a dispute over tolls. Harold is said to have laid waste to the region and to have ransacked the church of St Woolos but then to have made restitution for the attack and to have given an offering at the altar of the church. 
After the Norman invasion, in the early 1090’s, Robert fitz Hamon, earl of Gloucester, began the conquest of the lowland areas of Gwynllŵg and Morgannŵg, and there also appears to have been a punitive raid against the Welsh by William Rufus. Robert de la Hay controlled the land in southern Gwynllŵg as a fief from fitz Hamon, and it was likely that either Robert de la Hay or William Rufus had a motte (castle mound) built on Stow Hill. Sometime between 1094 and 1104 Robert de la Hay granted (or re-granted) the church of St Woolos to Gloucester Abbey. 
A charter of 1132 by Robert the Consul, earl of Gloucester, the illegitimate son of Henry I, gifted land in Malpas to Montacute Priory. In it is a reference to the Novo Burgo (i.e. the New Borough of Newport).  An important reason for establishing this new borough would have been to control the river crossing. The town also became a centre for trade and as the chief market town for the area would be useful to the lord in the collection of tolls.
Newport Castle became the administrative centre for the Norman lordship created from the former cantref of Gwynllŵg. The lordship of Newport was a ‘Marcher Lordship’ enjoying many of the rights and privileges of the former Welsh rulers.
In 1198 the lordship passed into the hands of Prince John through his wife Isabel. John became king in 1199 and soon after divorced Isabel, but retained her lands until 1214, when she remarried. The lordship passed to the important de Clare family in 1217 and remained with the de Clares until the death of the then lord, Gilbert de Clare III, in 1314 at the Battle of Bannockburn.
Newport suffered in the unrest involving the Welsh princes and the English barons. During a conflict in 1265 Simon de Montfort devastated the area and ‘spared neither women nor children’.  Again in 1296, 66 of the town’s 256 burgages were laid waste during warfare involving the Welsh lord Morgan ap Maredudd ap Llywelyn.  In 1316 there was further destruction during the rebellion of Llywelyn Bren. 
In 1317 the de Clare lands were split between Gilbert de Clare’s three sisters. The second sister, Margaret, received the marcher lordship of Gwynlŵg which became known as the lordship of Newport. She had married Hugh Audley, an important knight at the court of Edward II. However the elder de Clare sister, Eleanor, had married Hugh Despenser the Younger and he seized control of Gwynllŵg and Newport. Disputes over the territorial ambitions of Hugh Despenser led to conflict between leading barons and Edward II, and in 1321 Hugh Audley, together with his other brother-in-law, Roger Damory, besieged Newport Castle with a large force.
Following the defeat of Hugh Audley and other barons at the Battle of Boroughbridge in 1322, Hugh Despenser re-acquired his lands including the Lordship of Newport. In 1324 Despenser secured many privileges (including freedom from tolls and other customary dues) for seven Welsh boroughs, one of which was Newport. In 1327 Edward II was deposed and Hugh Despenser was executed, and Hugh Audley re-acquired the Lordship of Newport.
Hugh Audley in 1347 was succeeded by his son-in-law Ralph Stafford, first earl of Stafford. Staffords remained lords of Newport until 1521, when Edward Stafford, third duke of Buckingham, was executed. However there were long periods when the lords were minors, and Stafford lands were ‘farmed out’ by the king until the lord became of age.
Hugh, second earl of Stafford, gave Newport its first charter in 1385. Edmund, fifth earl of Stafford, was killed at the Battle of Shrewsbury in July 1403. In the same year Newport and Newport Castle were devastated during the rebellion of Owain Glyndŵr. Afterwards the Lordship of Newport was said to have no value to the lord because all was burnt, destroyed and wasted. 
Humphrey was created 1st duke of Buckingham in 1444. He died at the Battle of Northampton in 1460 and was succeeded by his grandson, Henry Stafford, who was a minor The the custody of Stafford estates was again farmed out. It was originally granted to Richard Neville, earl of Warwick, but in 1462 the farm was transferred to Sir William Herbert of Raglan Castle. Herbert was killed in July 1469 after the Battle of Edgecote. His lands, including the Stafford estates in South Wales, were seized by the earl of Warwick. It was Warwick who authorised in November 1469 payments for the ‘making of the ship at Newport’. Warwick was killed at the Battle of Barnet in 1471, and in 1473 Henry Stafford, second duke of Buckingham came into his inheritance.
The second duke was executed by Richard III in 1483. During the minority of his son, Edward Stafford, third duke of Buckingham, the lordship of Newport came into the hands of Jasper Tudor, earl of Pembroke and duke of Bedford, who in 1485 married Katherine Wydevill, the widow of the second duke of Buckingham.
The third duke of Buckingham came into his inheritance in 1498. In 1521 the duke was executed for treason and his lands then were seized by the crown.
The population of medieval Newport is not known. There were over 250 burgages (units of land held by the burgesses), but not all of them would have had houses, and not all dwellings were on burgage plots. This figure compared favourably with other Gwent towns. In the early fourteenth century Chepstow had 308 burgages, Newport 296 burgages, Trelech 275 burgages and Abergavenny 233 burgages.  The size of population must have fallen during the Black Death, and after attacks such as the Glyndŵr destruction of the town in 1403. Possibly there would have been a population of 1000 -2000 in more stable times.
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27 ( London 1860)
2. Garmonsway, G.N., (translator) The Anglo-Saxon Chronicle 170 (Dent: Everyman’s Library 1953)
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4. Coplestone-Crowe, B. ‘Robert De La Haye and the Lordship of Gwynllwg’ in Gwent Local History Number 85 (Autumn 1998).
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9. Calendar of Inquisitions Post Mortem 1-6 Henry IV. 1399-1405. 272
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Bob Trett 2010