Against the most powerful and most dangerous of the traitors, Robert of Bellême, Henry felt strong enough to take steps in the spring of 1102. In a court in that year Henry brought accusation against Robert on forty-five counts, of things done or said against himself or against his brother Robert. The evidence to justify these accusations Henry had been carefully and secretly collecting for a year. When Robert heard this indictment, he knew that his turn had come, and that no legal defence was possible, and he took advantage of a technical plea to make his escape. He asked leave to retire from the court and take counsel with his men. As this was a regular custom leave was granted, but Robert took horse at once and fled from the court. Summoned again to court, Robert refused to come, and began to fortify his castles. Henry on his side collected an army, and laid siege first of all to the castle of Arundel. The record of the siege gives us an incident characteristic of the times. Robert's men, finding that they could not defend the place, asked for a truce that they might send to their lord and obtain leave to surrender. The request was granted, the messengers were sent, and Robert with grief "absolved them from their promised faith and granted them leave to make concord with the king." Henry then turned against Robert's castles in the north. Against Blyth he marched himself, but on his approach he was met by the townsmen who received him as their "natural lord." To the Bishop of Lincoln he gave orders to besiege Tickhill castle, while he advanced towards the west, where lay Robert's chief possessions and greatest strength. In his Shrewsbury earldom Robert had been preparing himself for the final struggle with the king ever since he had escaped his trial in the court. He counted upon the help of his two brothers, whose possessions were also in those parts, Arnulf of Pembroke, and Roger called the Poitevin, who had possession of Lancaster. The Welsh princes also stood ready, as their countrymen stood for centuries afterwards, to combine with any party of rebellious barons in England, and their assistance proved of as little real value then as later. With these allies and the help of Arnulf he laid waste a part of Staffordshire before Henry's arrival, the Welsh carrying off their plunder, including some prisoners. Robert's chief dependence, however, must have been upon his two very strong castles of Bridgenorth and Shrewsbury, both of which had been strengthened and provisioned with care for a stubborn resistance.