Meantime, Ivo Taille-Bois, clad in his linked mail, and followed by armed men, rode to the abbey of Peterborough. On being admitted to the abbot's presence Ivo proposed an expedition to the Isle of Ely, to destroy the Camp of Refuge and crush the insurgents. Turauld sanctioned the expedition, but declined to take an active part in it; and everything having been arranged, the Angevin viscount advanced boldly with his men through the forests and willows which served the Saxons as intrenchments, while the abbot, surrounded by Normans of high rank, remained at what he considered a safe distance. But Ivo Taille-Bois was destined to miss his foes, and Turauld to meet those whom Ivo sought. Aware of the projects of the Normans and of their movements, Hereward was on the alert. Contriving to escape unobserved from the wood by one side while Ivo entered by the other, the Saxon chief, leaving the Angevin viscount to pursue his search in vain, fell suddenly upon the abbot and the abbot's Norman attendants, seized them without difficulty as prisoners, and kept them securely in the marshes till they paid a large ransom. Nevertheless, the position of Hereward and his comrades became every day more perilous. About this time, however, they were reinforced by allies, whose presence inspired them with some hope of accomplishing their country's deliverance. Indignant at his brother's conduct at York, Sweyn, King of Denmark, fitted out a new fleet, and came in person to the aid of the vanquished islanders. But the royal Dane soon tired of an enterprise which he found was much less promising than he had anticipated. After sailing up the Humber without receiving any particular encouragement, he returned to Denmark. But, however disappointed he might have been, Sweyn, while departing from the shores of England, did not withdraw his fleet. Entering Boston Wash, the Danish ships, by the mouth of the Ouse and the Glen, succeeded in reaching the Isle of Ely. Hereward hailed with joy the arrival of the Danes, and welcomed them as friends and liberators. William was startled at the arrival of Danish auxiliaries, but he was not particularly perplexed. Perfectly comprehending how to deal with King Sweyn, the Conqueror hastened to send ambassadors to Denmark with artful messages and costly presents. The successor of Canute, completely won over to the Norman cause, did without scruple that which he had, some months earlier, punished his brother for doing; and Hereward and his comrades soon learned to their dismay that they were once more betrayed by their Northern allies.