Thus, then, the great cause of ecclesiastical contention was removed, and we might expect that the joyful event would be celebrated by the marriage of the young affianced pair, Constantine and Hrotrud, now aged sixteen and fourteen respectively. On the contrary, this was the very year in which, after mysterious embassies backwards and forwards between the two Courts, the marriage treaty was broken off and the relations became more openly hostile than ever; but curiously enough (as is not unfrequently the case in such affairs) there is a conflict of testimony as to which side had the credit or discredit of breaking off the match. The Frankish annalists say or hint that Charles refused his daughter to the young Emperor, who was much angered by the refusal. A Byzantine historian says that “Irene broke off the treaty with the Franks and sent the Captain of the Guard to fetch a damsel from Armenia named Mary whom she married to her son the Emperor Constantine, he being much grieved thereat, and not liking his bride because his inclination was towards the daughter of Charles, King of the Franks, to whom he had been precontracted.” It is hopeless with our scanty materials to discover the reason of this mysterious rupture between the Courts. One of the most careful of the German writers who have treated of this period attributes it entirely to Charles’s invasion of Benevento and reduction of its prince Arichis to vassalage, which, as has been already related, occurred in the year 786. This, he considers, was a breach of the tacit agreement to maintain the Italian _status quo ante_ entered into in 781, and was resented accordingly. Others have seen in it a stroke of policy on the part of Irene, who was already becoming jealous of her son’s share in the Imperial authority, and feared to see him provided with a too powerful father-in-law. If it be permitted to hazard yet another conjecture, where all is conjectural, I would point out that in the interval between 781 and 787, Hildegard, the mother of Hrotrud, had died, and Charles had married another wife, the haughty and unpopular Fastrada. Possibly that proud and jealous woman resented the idea of seeing her little step-daughter raised higher than herself by her exaltation to the throne of the Cæsars, and may have used her influence with her husband to entangle still further the already ravelled hank of the negotiations with Constantinople, and at last in disgust to break off the match altogether? The whole story is a remarkable illustration of the fact, so clearly shown in the negotiations for the Spanish marriage of Charles I. when Prince of Wales, that a marriage treaty, if not very carefully conducted, is quite as likely to embroil two sovereigns as to unite them.[57]