In February, Flambard escaped from the Tower of London and crossed the Channel to Normandy, where he injected fresh direction and energy to Robert's attempts to mobilise an invasion force. By July, Robert had formed an army and a fleet, ready to move against Henry in England. Raising the stakes in the conflict, Henry seized Flambard's lands and, with the support of Anselm, Flambard was removed from his position as bishop. The King held court in April and June, where the nobility renewed their oaths of allegiance to him, but their support still appeared partial and shaky. With the invasion imminent, Henry mobilised his forces and fleet outside Pevensey, close to Robert's anticipated landing site, training some of them personally in how to counter cavalry charges. Despite English levies and knights owing military service to the Church arriving in considerable numbers, many of his barons did not appear. Anselm intervened with some of the doubters, emphasising the religious importance of their loyalty to Henry. Robert unexpectedly landed further up the coast at Portsmouth on 20 July with a modest force of a few hundred men, but these were quickly joined by many of the barons in England. However, instead of marching into nearby Winchester and seizing Henry's treasury, Robert paused, giving Henry time to march west and intercept the invasion force. The two armies met at Alton, Hampshire, where peace negotiations began, possibly initiated by either Henry or Robert, and probably supported by Flambard. The brothers then agreed to the Treaty of Alton, under which Robert released Henry from his oath of homage and recognised him as king; Henry renounced his claims on western Normandy, except for Domfront, and agreed to pay Robert £2,000 a year for life; if either brother died without a male heir, the other would inherit his lands; the barons whose lands had been seized by either the King or the Duke for supporting his rival would have them returned, and Flambard would be reinstated as bishop; the two brothers would campaign together to defend their territories in Normandy. Robert remained in England for a few months more with Henry before returning to Normandy. Despite the treaty, Henry set about inflicting severe penalties on the barons who had stood against him during the invasion. William de Warenne, the Earl of Surrey, was accused of fresh crimes, which were not covered by the Alton amnesty, and was banished from England. In 1102 Henry then turned against Robert of Bellême and his brothers, the most powerful of the barons, accusing him of 45 different offences.