When Leicester received the news of Edward's escape, he conceived that the prince was gone to join the Earl Warenne, and William de Valence, who a few days before had landed with one hundred and twenty knights on the coast of Pembrokeshire. Ignorant, however, of his real motions, he dared not pursue him; but issued writs in the King's name, ordering the military tenants of the Crown to assemble at first in Worcester, and afterward in Gloucester. To these he added circular letters to the bishops, accusing Edward of rebellion, and requesting a sentence of excommunication against all disturbers of the peace "from the highest to the lowest." The royalists had wisely determined to cut off his communication with the rest of the kingdom by securing to themselves the command of the Severn. Worcester readily opened its gates; Gloucester was taken by storm; and the castle, after a siege of two weeks, was surrendered on condition that the garrison should not serve again during the next forty days. Every bridge was now broken down; the small craft on the river was sunk or destroyed; and the fords were either deepened or watched by powerful detachments. Leicester, caught as it were in the toils, remained inactive at Hereford; but he awaited the arrival of the troops whom he had summoned, and concluded with Llewellyn of Wales a treaty of alliance, by which, for the pretended payment of thirty thousand marks, Henry was made to resign all the advantages which he and his predecessors had wrested from the princes of that country. At last, reinforced by a party of Welshmen, the Earl marched to the south, took and destroyed the castle of Monmouth, and fixed his head-quarters at Newport. Here he expected a fleet of transports to convey him to Bristol; but the galleys of the Earl of Gloucester blockaded the mouth of the Avon; and Edward, with the bravest of his knights, made an attempt on the town of Newport itself. The part which lay on the left bank of the Usk was carried; but the destruction of the bridge arrested the progress of the victors, and Leicester, with his dispirited followers, escaped into Wales.