In January 1532, Cranmer was appointed the resident ambassador at the court of the Holy Roman Emperor, Charles V. As the emperor travelled throughout his realm, Cranmer had to follow him to his residence in Regensburg. He passed through the Lutheran city of Nuremberg and saw for the first time the effects of the Reformation. When the Imperial Diet was moved to Nuremberg, he met the leading architect of the Nuremberg reforms, Andreas Osiander. They became good friends, and during that July Cranmer took the surprising action of marrying Margarete, the niece of Osiander's wife. He did not take her as his mistress, as was the prevailing custom with priests for whom celibacy was too rigorous. Scholars note that Cranmer had moved, however moderately at this stage, into identifying with certain Lutheran principles. This progress in his personal life was not matched in his political life as he was unable to persuade Charles, Catherine's nephew, to support the annulment of his aunt's marriage.