Soon after the Normal council at Windsor was over, a fresh military crisis erupted – or rather the embers of an old one were kindled back into flame. Despite the deal struck the previous year, the Viking army sent by King Swein of Denmark had not returned home. Their plan all along, it seems, had been to establish a base in northern England from which Swein could personally lead an outright conquest, and, at some point towards the end of May 1070, the Danish king finally arrived, joining his brother Asbjorn at the mouth of the River Humber. His reception, according to the Anglo-Saxon Chronicle, was rapturous. Although the English leaders had either fled or surrendered at the start of the year, the local people came out in support of the invader, assuming that he would carry all before him. Swein himself seems to have remained near the Humber, but Asbjorn and a force of Danish housecarls immediately moved south into East Anglia and seized the town of Ely. Here too there was reportedly a great surge of goodwill among the natives, and optimism about what portended. ‘Englishmen from all over the fenlands came to meet them’, says the E Chronicle, ‘thinking that they were going to conquer the whole land.’

One Englishman who was particularly enthusiastic about the prospect of a Danish takeover was Hereward, known to posterity as ‘the Wake’. Of all the figures who chose to resist the Normans, Hereward is arguably the most famous, but sadly his fame derives almost entirely from stories written down several generations after his own day, by which stage they had already taken a legendary turn. The twelfth-century Gesta Herewardi, for example, contains a few elements that appear to have some basis in fact, but too many escapades involving witches, princesses and monsters to be taken seriously as a historical source. Even Hereward’s arresting cognomen, once taken to indicate an exceptional level of alertness, is not recorded until the thirteenth century, and probably signifies nothing more than his supposed connection with the Wake family of Lincolnshire. The most we can say about Hereward is that, despite an uncertain ancestry, he seems to have been a man of noble status; apparently in exile at the time of the Conquest, he had returned to England at some point after 1066 to discover the Normans had killed his brother and seized his estates. Certainly when he enters the historic record in the summer of 1070, Hereward is already an outlaw.

Having described the arrival of the Danes in East Anglia, the E version of the Anglo-Saxon Chronicle reports that ‘Hereward and his gang’ were planning to plunder the monastery at Peterborough (where the E chronicle was later copied and interpolated, hence its detailed description of these events). It seems that they were motivated not only by the Danish invasion, but also by the knowledge that Peterborough had recently been committed to a new Norman abbot. Determined to score another victory against his oppressors, Hereward resolved to ransack the abbey ahead of the newcomer’s arrival. Despite the best efforts of the monks, who sent for help and resisted for as long as they could, Hereward and his followers eventually forced their way into the town of Peterborough and reduced much of it to ashes. They then entered the abbey church and seized its treasures – crosses, altar-fronts and shrines, all made of gold and silver, as well as money, books and vestments – which they carried off in triumph to the Danish camp at Ely. ‘They said they had done this out of loyalty to this monastery’, says the E Chronicle with evident bitterness. Hereward and his companions appear to have convinced themselves, if not the monks, that they were acting like prototype Robin Hoods, confiscating the abbey’s valuables to save them from expropriation by rapacious Normans. It was not, to be fair, a wholly implausible pose: Hereward and his men were tenants of the abbey, and the Conqueror’s raid on English monasteries at the start of the year was still fresh in everyone’s memory.

Having torched the town and looted the abbey, there may have been some talk among the outlaws and their Danish allies of holding Peterborough against the Normans. The E Chronicle says that ‘the Danes, thinking they would get the better of the French, drove out all the monks’. Yet when the new incumbent, Abbot Turold, arrived a short time later, he found the place deserted, the raiders having returned to their ships. Turold, it must be said, was no ordinary monk: William of Malmesbury later described him as acting ‘more like a knight than an abbot’, while the Chronicle calls him ‘a very ferocious man’, and reveals that he arrived to take up his post accompanied by no fewer than 160 fully armed Frenchmen. All the same, it says little for the reputation of the Danes and their English allies that they chose to flee from a monk, however fearsome, and what was, in relative terms, a small Norman force.

In truth, Danish dreams of conquest had probably died many weeks earlier. It seems likely that on his arrival in England Swein had found the forces under his brother’s command in an extremely sorry state. Orderic Vitalis provides a long description of the privations they had suffered during the winter as a result of storms and starvation. ‘Some perished through shipwreck’, he says. ‘The rest sustained life with vile pottage; princes, earls and bishops being no better off than the common soldiers.’ This is almost certainly a borrowing from William of Poitiers, for it is clearly heavily biased. At one point, for example, we are told that the Danes could not leave their ships for fear of the inhabitants, which is hardly the impression given by the Anglo-Saxon Chronicle. Moreover, the same account misleadingly omits all mention of Swein’s own arrival, saying only that the remains of the Danish army returned home to tell the king the sad story of their losses. Nevertheless, even when all such allowances are made, the essential point that the Danes were in trouble is likely to be true enough. In the wake of the Harrying it must have been very difficult for these men to have found sufficient food to sustain themselves.

Swein must have quickly realized that the remnants of his great fleet were inadequate for mounting a conquest: seen in this light, his decision to send Asbjorn into East Anglia looks less like the start of a military campaign, and more like a conventional Viking raid intended to recoup costs. At some point soon after the attack on Peterborough (which occurred on 2 June), William offered terms, and the Danish king readily accepted. His fleet sailed around the east coast, put into the Thames for two nights, then sailed back to Denmark. By midsummer, barely a month since his arrival, Swein was gone, leaving his English supporters high and dry, their hopes of regime change once again confounded. If Hereward and his fellow outlaws had ever truly regarded themselves as simply the temporary trustees of Peterborough’s treasures, now was the moment that they were disabused. ‘The Danes left Ely’, says the E Chronicle, ‘taking all the aforementioned treasures with them.’ The monks had to console themselves with the knowledge that their plunderers did not go unpunished. On its return voyage the Danish fleet was scattered by a great storm, so that only a small fraction of the booty ended up in Denmark, and even that little was lost to fire a few years later. Earl Asbjorn, meanwhile, was accused of having compromised the invasion by accepting William’s bribes, and sent into exile.