To the threatening attitude of France and Anjou was added, as a natural consequence, a conspiracy among the Norman barons, headed by the arch-plotter Almeric and the young Count Waleran of Meulan, a son of Henry’s own familiar friend. Their scheme, planned at a meeting held in September at the Croix-Saint-Leuffroy, was discovered by the king; he marched at once upon Waleran’s castle of Pontaudemer, and took it after a six weeks’ siege, during which he worked in the trenches as hard as any young soldier. This success was counterbalanced by the loss of Gisors, which was taken and sacked by Almeric; Henry retaliated by seizing Evreux. Advent and a stormy winter checked the strife; one battle in the spring put an end to it. On March 25, 1124, the rebels were met at Bourgthéroulde by Ralf of Bayeux, who commanded at Evreux for King Henry; despite their superior numbers, they were completely defeated, and Waleran was taken prisoner.[597] His capture was followed by the surrender of his castles; Almeric, who had as usual escaped, again made his peace with Henry; and the Clito’s cause, forsaken by his Norman partizans, was left almost wholly dependent on the support of Anjou.[598] Meanwhile Henry had found an ally in his son-in-law and namesake the Emperor, and in August France was threatened with a German invasion. Louis seized the consecrated banner--the famous Oriflamme--which hung above the high altar in the abbey of S. Denis, and hurried off with it, as Geoffrey Martel had once ridden forth with the standard of S. Martin of Tours, to meet the foe. But the invasion came to an unexpected end. For some reason which is not explained, the Emperor turned suddenly homeward without striking a blow.[599] [597] Eng. Chron. a. 1124. Ord. Vit. (Duchesne, _Hist. Norm. Scriptt._), pp. 876–880. Will. Jumièges Contin., l. viii. c. 21 (_ib._ p. 302). The date comes from the Chronicle; the continuator of Will. Jumièges makes it a day later. [598] Ord. Vit. (as above), pp. 880–882. [599] Suger, _Vita Ludov._, c. 21 (_Rer. Gall. Scriptt._, vol. xii. pp. 49, 50). The English king found a more useful friend in the Pope than in the Emperor. By dint of threats, promises and bribes, he persuaded the court of Rome to annul the marriage of Sibyl and the Clito on the ground of consanguinity.[600] Of their kinship there is no doubt;[601] but it was in exactly the same degree as the kinship between Henry’s own son and Sibyl’s sister, to whose marriage no objection had ever been raised. The Clito refused to give up his bride, and was thereupon excommunicated by the Pope;[602] Fulk publicly burnt the letter in which the legate insisted upon the dissolution of the marriage, singed the beards of the envoys who carried it, and put them in prison for a fortnight. The consequence was an interdict[603] which compelled him to submit; the new-married couple parted, and William the Clito became a wanderer once more.[604]