Archaeological and other evidence has led to the conclusion that parts of Anglo-Saxon Norwich north of the river had burh defences. Some have tried to argue for something similar around part of the settlement south of the river, but there is no conclusive evidence. Whatever the case, between the tenth and twelfth centuries, settlement greatly outgrew the borders of the defensive ditch, and what became the city's principal marketplace also arose outside the defended area. Had there been burh defences in the southern (Conesford) sector of Norwich, the construction of a Norman castle and cathedral there would have compromised them.

The castle proved less protection than liability, for in 1075 its constable, the earl of East Anglia, rebelled against William I, whose forces then laid siege to the castle, thus bringing war right into the centre of the city. The devastation and depopulation reported in Domesday Book is partly attributable to that event. In 1174 yet another rebellious earl of the region, in the context of the war between Henry II and his sons, led a force of Flemings in an attack on the city; chronicler Jordan Fantosme explained its fall by noting that the defenders were largely weavers, not trained soldiers. Again in 1217, in the context of the baronial rebellion against John, supported by Prince Louis of France, the latter's forces seized the castle and plundered the city. Nor did the castle prove much help in 1266, when disaffected barons (remnants of the Montfortian cause) again targeted Norwich and were able to carry off several wealthy citizens with a view to ransom. These disasters must have left their mark on the communal psyche.

Reducing Norwich's vulnerability to hostile forces was only one of the potential motivations behind creating a new defensive perimeter. There was also the question of channelling land-based commerce through a limited number of entry/exit points where tolls might be collected, of reflecting a sense of unity and identity in a town taking shape as a self-governing community, and of asserting claim over some of the lands surrounding the settled areas, over which jurisdiction was disputed with neighbouring settlements, but into some of which urban settlement had spread.

It was in the context of the last that we learn of a civic initiative to construct a defensive bank and ditch around the city in 1253, subsequent to licence obtained from the king to enclose it. For the cathedral-priory complained the new circuit encompassed lands it held on the northern and eastern outskirts of the urban settlement that were previously part of other hundreds and cut through the Prior's land at Pockthorpe, as well as taking in lands belonging to the Prioress of Carrow at the southern end of the city and to the hundred of Taverham west of the settled area. This land-grab created an urban jurisdiction larger even than intra-mural London, although Norwich had a much smaller population. However, to be fair, we should note that the extensive line of the walls served to protect not only the heavily populated areas of Westwick, northern Conesford and southern Coselany, but also to encompass southern (riverside) Conesford, which might otherwise have been left as a suburb were it not for the fact that many of the leading merchants had houses and warehouses by the waterfront, and several public quays were there, making this neighbourhood economically important to the city.

There is little reason to doubt that the line of this ditch and bank was the same as that of the later stone walls. A petition of the city, seeking the king's protection against legal action taken by the complaining rural jurisdictions, refers to nine gates being incorporated in the perimeter. It justified the enclosure on the grounds of security – the strategy apparently being to channel attack towards the gates, at which the citizens could concentrate their defensive forces – and controlling traffic into the city. The inadequacy of these defences must have been revealed by the events of 1266.

But the city government does not seem to have taken any action until the 1290s. In 1297 the king granted murage and authorized city authorities to compel all residents to contribute towards the costs. This suggests that efforts to proceed with erecting a stone wall atop the bank had already begun – maybe in 1294, as Blomefield claimed, or perhaps even earlier – but had not made much progress. Ca. 1300 it was decided to erect a special office in the marketplace for collecting the murage, with market stalls housed in the lower of two levels; this increased the overhead of the project. The murage grant was renewed in 1305 for five years, but at its conclusion no further renewal was granted. Perhaps Norwich's populace was balking at the cost; in 1305 there had been complaints about excessive taxation (renewed in 1307) and misappropriation of public revenues, and in 1308 the authorities had to obtain explicit approval from the king to compel all non-resident owners of property within the city to contribute to taxes levied to support wall-building. Had there been similar complaints about murage, the king would likely have suspended renewal, pending an audit of muragers’ accounts. However, the crisis of confidence passed, and murage was once more granted in 1317, this time for three years.

The line along the south-west side of the city probably received the most attention in the early stages. Although added impetus to strengthen the defences may have come from developments in the war with France, particularly the news of the French raid on Southampton ( 1338) and its adverse impact on local business, progress on Norwich's walls was evidently unsatisfactory. The insufficiency of murage revenues and unpopularity of taxes likely explain why this work dragged out and perhaps even stalled, until Richard Spynk took a hand.

Richard Spynk was purportedly born in Doddington, in the Isle of Ely, an estate under the lordship of the Bishop of Ely. By the time we see him at the apex of his career, in the 1340s, he was the owner of lands at March (alias Marcheford), a village near his birthplace, large enough to accommodate a small flock of cattle and a larger flock of sheep, and other property at Dickleburgh, a small market town some 27 miles south of Norwich, as well as land in the close vicinity of Norwich. It was Norwich Richard had made his home base, taking up the franchise there. His brother William seems to have been a partner in these initiatives. There may already have been a branch of the family established in the city, for ca.1324 a Norwich merchant, Robert Spynk, acquired property in St. Michael de Coslany parish (and more ca.1335), and Richard Spynk's interest in the same parish is indicated by the licence he obtained from the king (at the request of the Earl of Arundel) in July 1340 to grant in mortmain a parcel of land for the parish priest to build a parsonage; ca. 1336 Richard is seen acquiring property in that parish, and again – this time with a wife, Emma – in 1339/40. A reference of 1334 appears to be the earliest mention of Richard Spynk, when he (described as of Marchesford) acquired property in St. Augustine's, another Coslany parish; this was through a grant to his wife Emma by her parents, and may suggest a dowry. Emma's father, John Iringe, a dyer, also had quite a bit of property in St. Michael de Coslany; he was prominent enough to serve as a city bailiff in 1340. In 1339 we hear of a William Spynk, a fuller who is described as "from Weston", acquiring property in yet another parish in the Coslany area of Norwich. Family interests remained principally in that part of the city throughout the century.

Judging from the sheep he owned and his involvement in importing large quantities of woad through Ipswich in 1345, Richard Spynk must have been active in aspects of the cloth trade. Ca.1340 Andrew Manner released Spynk from any claims that might have been made in relation to his recent apprenticeship. Spynk's marriage to the daughter of a dyer also supports the notion of a business related to cloth or its ancillary trades. At any rate, his business so prospered that, to judge from his assessment in a local tax levied in 1350/51, he must have become one of the wealthiest citizens. Despite his wealth and his public-spiritedness (also evidenced by his donation, in 1344, of a paper volume for the recording of municipal memoranda), he is not known to have held political office in the city, although his son Thomas Spynk was bailiff in 1375/76 and 1381/82. Richard's wealth, along with his business acumen, is evidenced in his initiative to help along the completion of the construction of Norwich's defences.

In 1337 the Norwich authorities had obtained from the king a renewal of the right to collect murage, for 5 years, to finance work on the city walls. But, in part because the king had also granted exemptions from paying murage to citizens of other of his boroughs, the revenues from this source were not up to the task. The city authorities therefore resorted to levying a local tax – its royal charter of 1305 having included the power to raise taxes at need (with the consent of the community) for purposes related to "the protection and common utility of the City" [Hudson and Tingey, op.cit., vol.1, p.20], along with the right to compel citizens to pay their share. In fact, they levied a series of taxes over the same period as the murage.

Richard Spynk became involved to enable the proceeds to be more quickly realized. Rather than an outright donation, it seems he first proposed advancing the city government some part of the total amount assessed; this loan (as it was described at first) to be repaid once the assessments were able to be collected. It was by no means unknown for boroughs to borrow cash from citizens and repay them out of annual revenues. There was evidently some master-plan of what work needed to be undertaken, although whether this originated with Richard or with the city authorities is unknown; the consistent architectural style of the walls, built over several decades, suggests that the plan existed prior to Richard's time. Richard's sponsorship of the project extended to donating his time and energy to coordinate the construction work. Despite the £100 that the bailiffs were able to chip in, presumably from proceeds of the tax, the arrangement with Richard was compromised when other of the wealthier citizens tried to avoid having to pay their assessments, by withdrawing themselves from the city (perhaps relocating to property in the countryside). The authorities sought, and on 3 December 1343 obtained, from the king a writ confirming their right to oblige the delinquents to pay, so that Richard could be reimbursed.

Yet the document given above, only a few days after the issue of the king's writ, indicates a change of tack. Richard, it appears, was now prepared to portray his loan as a donation, in return for certain privileges that would in time allow him to recoup the outlay. The deal he struck was a shrewd one, and we should not forget that the work of completing the walls was of greatest benefit in that part of the city where Richard and his family owned property, but none of this necessarily dampens the impression of a man genuinely interested in the welfare of his community. Further evidence of that is in Richard's purchase and gift to the city in 1344/45 of a paper book (now known as the Old Free Book) to serve as a volume of memoranda – that is, of copies of documents important to the city. The documents recording Richard's work on the walls and the city's commitments to him were among the first to be copied into the book. They were joined by documents relating to the city's financial liabilities in 1344, the king's confirmation (1330) that the city government could put to profit any vacant land within its jurisdiction, and lists of electoral results, among other records. This book and the walls are both reflections of a sense of corporate self-confidence in this period, just before the crushing blow struck by plague.

Misfortune struck at Richard Spynk, however, before the arrival of the Black Death. The exceptional nature of his financial support of his community, as reflected in the high-powered witness list to the document recording that support, may have been what attracted unwelcome attention. This came from Thomas de Lisle, who was made Bishop of Ely in 1345. The following year saw a series of complaints to the king from Richard and his brother William, alleging that the Bishop had incited some of his officials and tenants to conduct a campaign of intimidation against them: stealing oxen, sheep, and cattle from their rural property, ambushing them near that property on several occasions and threatening them with death, mutilation or imprisonment, assaulting their employees and servants, and laying siege to them at Norwich and Dickleburgh, so that they were unable to issue forth to pursue their business.

These allegations set off a legal battle lasting several years and causing so much trouble that it eventually came before parliament. Part of the Bishop's argument was that the Spynks had been born his villeins, and had no legal right to bring charges against their lord; he claimed that they were suing him only as a trick to allow them to claim free status, by having a court give cognisance to their case. Richard responded that he was a free man, not a villein, and asked parliament for the benefit of the doubt that would allow him to pursue his complaint; this proved a tactical error, for the lords were already concerned about the issue of villeins seeking to win freedom by false means (such as by fleeing to towns), and they rejected the Spynks' complaints.

Richard was obliged to reach an out-of-court settlement – arbitrated by the same Earl of Suffolk who had been a witness to Norwich's acknowledgement of Richard's beneficence – whereby, in exchange for payment, the Bishop conceded him a manumission; we should not take this as Richard's admission of having been born unfree, but rather as the only means to get the Bishop off his back. The case, along with others involving de Lisle, has been investigated by John Aberth [Criminal Churchmen in the Age of Edward III: The Case of Bishop Thomas de Lisle, Pennsylvania State University Press, 1996], who concluded that while the hard-up Bishop might have been pursuing a legitimate claim of villeinage over the Spynks, his career in general suggests it was an attempt to extort, through intimidation, money from a man of demonstrated wealth. He could get away with it against a mere townsman, but shortly after he came to grief when he tried similar tricks against a cousin of the king.

The end-product of the effort stretching over half a century of Norwich history was about 2.3 miles of wall, with the original nine gates, presumably timber, now substantially strengthened and supplemented by two postern gates and the gateway protecting Bishop's Bridge. None now survive. Over 40 towers were spread around the circuit. Only a small stretch of wall between Barre Gate and the river remained to be built, which may not have been accomplished until the 1370s or '80s. The wall appears to have been about 12 feet in height and 3 feet thick. A walkway beside the wall proper was carried on stretches of arcades; on the interior side of the arches arrow-loops pierced the wall, and a few loops for early artillery were also incorporated. The ditch (judging from the findings of one excavation) would have been about 60 feet wide and 12 feet deep, and possibly water-filled in parts low enough to be fed by the river. This may not have been the mid-thirteenth century ditch, however, for in 1343 a seven-year grant of murage was specifically for making a ditch to support the walls; the grant implies there was open access to the walls, so perhaps the earlier ditch was considered too shallow – evidently it had not held off the attackers in 1266 – or was dry and perhaps infilled, and the intent now was to make it a more formidable barrier.

Richard Spynk's work on the northern stretch of wall was essentially to complete the circuit, since the north-eastern stretch between Barre Gate and Fybriggate Gate had been completed ca.1331, and to strengthen the existing gatehouses. The particular effort made in this part of the city at Richard's own expense likely owed something to the fact that he and his family lived there.

Why there should have been a stretch of wall built near Roscelin's Staith is unclear. Historians have always assumed that city policy was to rely on the river itself as a protective barrier on the east side of the city. Possibly there was some notion of building a continuation, down into Conesford where many of the wealthier merchants had houses and warehouses, of the cathedral precinct wall, but inadequate funding prevented realization. Whatever the reason, it appears this stretch of wall was still being maintained by 1451, when responsibility for that lay with the ward of Middle Wymer. A reference in 1378 to a wooden paling on the riverbank may indicate a less sturdy defensive line there.

It would seem that the western of the two towers that later became known as the Boom Towers was already in existence; their purpose, to repulse assailants coming up-river. Whether it was Spynk's own idea to strengthen this defence by building the second tower and stringing the chains between them as an obstacle to ships, we cannot know. This device might have been useful for controlling river-borne commerce as well, although whether the chains were raised for that purpose, or kept strictly for military defence, is uncertain; Kirkpatrick's assertion that the chains were there to enforce tolls has been repeated by other historians since, but I have not encountered any substantiation.

Spynk's single largest contribution was perhaps in constructing the fortified gateway at one end of Bishop's Bridge. A bridge had been in existence for almost a century and must have been reasonably sturdy, for the city had in 1331 acknowledged the Prior's right to build a gateway on it; whether he did so or not is unknown. Richard Spynk is generally credited with building the stone and brick bridge which remains the basis of what stands today. Most probably what he did was rebuild the bridge so as to provide the necessary reinforcement to support the towering gate. It has been suggested that male and female faces carved into one of the arches of the bridge may represent Richard and his wife, as an acknowledgement of their sponsorship (just as lay sponsors of church-building were sometimes credited by depicting them in stained-glass windows).

The emphasis on the gates – strengthening them with portcullises (and in the case of the principal entrances with adjoining towers) and equipping them with springalds – is a further indication that these were intended to be the primary points of resistance in the event of a siege; the ditch provided an unappealing obstacle to attacking forces, encouraging them to focus their efforts on capturing a gate and obtaining entrance into the city thus. Richard Howlett ["Norwich Artillery in the Fourteenth Century," Norfolk Archaeology, vol.16 (1906), 61] theorized that Spynk's springalds were distributed fairly evenly around the walls, two to each of the main gates, but six each to Berstrete Gate and the Black Tower (between Berstrete and Conesford Gates). Bearing in mind that past attacks on Norwich, by sea or land, had come from the south, and allowing for the fact that access from the south via the Yare/Wensum was now blocked at the southern end of the wall, the bailiffs evidently considered that the southern stretch of wall was most likely the first line of defence and armed it accordingly. The city was not sufficiently well defended to hold off any army seriously intent on capturing it, but the hope was probably that it could offer enough resistance to repel poorly armed or untrained forces, or to persuade raiders and even invading armies to move off to find easier prey.

The city authorities were presumably well-intentioned when they provided Richard Spynk with assurances, and put in place mechanisms, for keeping the walls and ditches in good shape. This resolve, perhaps originally prompted by fears of French invasion, may have weakened in the face of the expense involved in maintenance, and the lack of further threats from any attacking army, other than that of the peasants of 1381. In 1378 ditches were said to be clogged and walls in disrepair; the bailiffs were ordered to remedy the situation. In this period, a number of the towers and chambers above the gates had been leased out to citizens for private purposes; the city treasurers' accounts for 1378/79 identify ten such lessees, including the incumbent warden of the ditches. The gates themselves, and the toll collection associated with them, were also being leased out during Richard II's reign; an entry in a court roll for 1390/91 has a man fined for apparently redirecting customers headed for one gate towards other gates, to the financial loss of the lessee of the former.

With the threat from France continuing to hang over English heads, and further nervousness prompted by the Peasants' Revolt, there was renewed attention to defensive matters. The city treasurers accounts reveal precautionary measures: provisions for allocating townsmen to defend the walls and the purchase of materials for gunpowder (1384/85), work underway on several parts of the city ditch (1385/86), possibly widening and/or deepening, and two masons paid 12d to perform a one-day survey of the walls (1386/87). In 1392 the city received a grant of land in mortmain to provide a new source of revenue to support wall maintenance, and for the same end the king granted (1410) ulnage for seven years.

But the fifteenth century on the whole shows little evidence of continued effort to maintain the defences. Not until the time of the Wars of the Roses do we find explicit provisions for the various wards of the city to take responsibility for repairing specified stretches of wall, along with their gates and towers. This system may have been effect in earlier decades – fines imposed on those failing to show up for major work on Coslany Gate in 1420/21 imply communal labour – but the possibility that it was an innovation is suggested by indications that the citizenry were resisting this duty. For, about a year later (ca. 1452) the king authorized mayor and sheriffs, along with a commission of six of the leading citizens, to compel, under threat of distraint or imprisonment, all resident merchants and craftsmen to contribute to the repair of walls and towers and the cleaning of the ditches and river. Walls and towers were described as broken and ruinous and rivers and ditches obstructed by weeds and by rubbish that had been dumped in them. The intent here was not for the citizens to carry out the work, but to pay towards the hiring of labourers and carts. It is not clear whether the concern underlying this initiative was that of the king or the city authorities, for Norwich was never in jeopardy during the civil war, and changes in siege technology made the wall a less daunting obstacle than it would have been ca.1344, although even then it was more a demotivating deterrent than an impregnable defence.