Thus by the beginning of February, 1217, Louis’s mastery of eastern England was completed, seemingly without a struggle. At first glance, the action of Henry’s representatives seems unaccountable; there is, however, reason to think that it was really part of a scheme for bringing the desultory war to a crisis. Their aim seems to have been first to induce Louis to scatter his forces, and then to lure him back to the coast, hoping that there they might either cut off his retreat, or compel him to return to his own country.[91] For the accomplishment of this design it would be necessary to concentrate their own forces; and this could only be done by withdrawing the garrisons from such of the royal castles as were least worth retaining at the moment. These were the castles of East Anglia and Essex. Unlike the fortresses of the west, which it was of paramount importance to maintain in a state of efficiency as a protection against encroachments of the King’s enemies from the Welsh border, these eastern castles were practically isolated outposts in a district of which the greater part was under the enemy’s control. Surrounded as they were by the territories of powerful barons who supported Louis, they were not available as bases for concerted action; and the stores, arms, horses, and men in them could be made far more useful elsewhere.[92] To the enemy, on the other hand, the bait would be a tempting one; and the possible consequences of taking it might well have escaped the penetration of a more wary general than was Louis of France at this stage of his career. The possession of these castles placed the whole of eastern England under his uninterrupted sway, and removed all serious obstacles, except one, to his communications with his allies in the north. That one obstacle was the castle of Lincoln, which under the command of a woman had hitherto resisted every assailant. Louis appears to have made a circuit of his new possessions--no doubt placing a garrison in each of them--and then proceeded to Lincoln, hoping that his personal presence and the isolation in which she was now placed might tempt or frighten Dame Nicolaa into a betrayal of her trust. In this hope he was disappointed. The city received him, as it had already received his adherents; but the castle “held out,” for the Dame “kept it very loyally.” Louis could only return to London and thence send the castellan of Arras to take up his quarters in Lincoln city, that he might “hold the country with the help of the Northerners.”[93]