The castle was long considered impregnable; and to it Queen Isabel fled with Sir Roger Mortimer, whom she had created Earl of March, and she held it with a guard of one hundred and eighty knights. King Edward III with a small retinue occupied the town. Every night the gates of the fortress were locked and the keys delivered to the Queen, who slept with them under her pillow. Sir William Montacute, with the sanction of the young king, summoned to his aid several nobles on whose fidelity he could depend, and obtained Edward's warrant for the apprehension of the Earl of March. The plot was now ripe for execution. For a time, however, the inaccessible nature of the castle rock, and the vigilance with which the gates were guarded, appeared to present an insuperable obstacle to the accomplishment of their designs. However, Sir William Eland, Constable of the Castle, was won over, and he agreed to admit the conspirators. In the words of an old chronicler, the Constable said to Montacute, "Sir, woll ye unterstande that the yats (gates) of the castell both loken with lokys, and Queen Isabell sent hidder by night for the kayes thereof, and they be layde under the chemsell of her beddis-hede unto the morrow ... but yet I know another weye by an aley that stretchith out of the ward, under the earthe into the castell, which aley Queen Isabell ne none of her meayne, ne the Mortimer, ne none of his companye knoweth it not, and so I shall lede you through the aley, and so ye shall come into the castell without spyes of any man that bith your enemies." On the night of October 19, 1340, Edward and his loyal associates before midnight were guided through the subterranean passage by Eland, and burst into the room where the Earl of March was engaged in council with the Bishop of Lincoln and others of his friends. Sir Hugh Trumpington, Steward of the Household, a creature of Mortimer, attempting to oppose their entrance, was slain. The Earl himself was seized, in spite of the entreaties of Isabel, who, hearing the tumult, rushed from her chamber, crying "Fair son, spare my gentle Mortimer!" Both were secured. The next day, Edward announced that he had assumed the government, and summoned a Parliament to meet at Westminster on the 26th November. No sooner had this Parliament met than a bill of impeachment was presented against Mortimer. The peers found all the charges brought against him to be "notorously true, known to them, and all the people." And he was sentenced to be drawn and hanged as a traitor. Mortimer was executed at Tyburn, and the Queen Mother was sent under ward to the manor of Rising. The passage by which the conspirators entered, and by which the Earl was conveyed away, goes by the name of Mortimer's Hole to the present day.