BRIDGES AND BURHS

The most successful way to thwart the Vikings was to build fortifications; even the Great Army was incapable of taking strongly held defences. However, this required the mobilization of manpower and the overcoming of local apathy. Charles the Bald concentrated on blocking the Seine, which led to the heart of his kingdom. In 862, he began work on a fortified bridge at Pont de l'Arche near Pîtres, consisting of a wooden superstructure and bridgehead forts of wood and stone. In 865, Vikings were still able to reach Paris, so Charles went to Pîtres with workmen 'to complete the fortifications, so that the Northmen might never again be able to sail up the Seine'. Yet in 868 'he measured out the fort into sections ...and assigned responsibility for them to various men of his realm', and the next year men were detailed 'to complete and then guard the fort' (Annals of St Bertin). The work seems finally to have been completed by 873. This was part of a campaign of fortification. In 864, Charles ordered that men too poor to campaign were to work on and garrison fortifications, and in 865 bridges were rebuilt to block access to the Oise and Marne. The monastery of St Denis near Paris was walled in 869, and a fortified bridge was built at Paris. He also ordered the restoration of walls at Tours, Le Mans, and Orleans in 869, and a bridge was built at Pont-de-Ce to block the Loire. Before Charles went to Italy in 877 he showed continuing concern by issuing instructions for garrisons and the inspection of defences. However, in 885 the Great Army sailed up the Seine to Paris. Since the death of Charles in 877, royal power had declined, and Pont de l'Arche was probably no longer garrisoned. At Paris, effective resistance was led by the local commanders abbot Gauzlin and count Odo. During the 88Os, defences were constructed throughout the area between the Seine and Rhine, but now it was on local rather than royal initiative.

In England, Alfred's contemporary biographer Asser wrote of 'the cities and towns he restored, and the others he constructed where there had been none before'. The Burghill Hidage, an early tenth-century document, lists thirty West Saxon burhs (fortresses) and the number of hides (a measure of land for assessing taxes and dues) attached to each to provide manpower. Each hide was to send one man with responsibility for four feet of rampart, and where the walls survive their length often corresponds closely to the allotted garrison. Although changes had occurred by the early tenth century, there is little doubt that the system originated in the 880s. The burhs had several functions. They were refuges for the local population, their garrisons ensured the Vikings could not seize them, and men from the burhs were a mobile reserve which could be used against raiders, as in 893. They had various origins: reused Roman walls, earthworks from the Iron Age and later, and new foundations. Some were small forts close to existing sites, but others like Wallingford were founded as new towns with planned layouts. The Burghill Hidage arrangements required the mobilization of 27,000 men - perhaps one-fifth of the adult male population of Wessex. Unsurprisingly, there was some apathy in face of such a demand: in 892, the Great Army overran a half-made burh (probably the lost Eorpeburnan in East Sussex) which contained an incomplete garrison. Yet generally the system worked. Whereas in the 870s the Great Army seized existing forts at will, from 884, when it vainly besieged Rochester, it was unable to penetrate the heart of Wessex.