These circumstances induced the Cardinal in the course of the year 1585, to think seriously of obtaining a dispensation, to enable him to quit the priesthood, give up his cardinal's hat, and marry. Before taking this extreme step however, he determined on endeavouring, if possible, to persuade his brother, Don Pietro, to marry. This was very difficult to do. For though Pietro hated his eldest brother and Bianca quite well enough to be ready to do his best to counteract their plans, he cared nothing for the family name or greatness; and the extreme profligacy of his life made marriage extremely distasteful to him. He alleged in reply to the Cardinal's instances, that the vow he had made to the Virgin, on the occasion of murdering his wife, stood in the way. He had solemnly promised not to marry again, and could not charge his conscience with the breach of so solemn a vow. He added, to save trouble, that no theologian would succeed in persuading him,[210] that the engagement so undertaken was not valid. Nevertheless, he at last consented to do as the Cardinal would have him; and accordingly set on foot negotiations for obtaining the hand of a lady of the Spanish court. Having done this much however, he seemed to be in no hurry to conclude the matter, and continued his usual dissolute life in Florence.
At length, about the middle of November, 1585, he so far yielded to the urgent representations of the Cardinal, as to announce his intention of starting for Spain, to conclude in person the arrangements for his marriage. But about a month later, while he was still waiting for the passage of the Spanish galleons, the news was suddenly spread over Tuscany, that the Grand Duchess had had a miscarriage while staying at Cerreto. Cerreto was a remote villa belonging to the Grand Duke, in the hills, near Empoli, in the lower Valdarno. Some writers assert, that it was in this lonely old castle, and not at Poggio Imperiale, that Paolo Giordano Orsini murdered Isabella. At all events, the place was well adapted for the perpetration of such a deed; and it would seem to have no recommendation save its remoteness, which could have induced Bianca to select it as the scene of her confinement.