Suspected, however, of sympathizing with the reformers, he deemed it prudent to leave Paris, and in 1535 went to the East with his cousin Jean de La Forest, the first French ambassador at Constantinople.
Cunning and ambitious, he soon made his mark, and his cousin having died during his embassy, Marillac was appointed his successor.
He is known to have sent dispatches back to France detailing events such as the king's first meeting with his fourth wife Anne of Cleves, which resulted in the sudden downfall and demise of the seemingly all-powerful Thomas Cromwell, who was responsible for the ill-fated marriage.
[2] While Henry, at first sight, found Anne of Cleves so unattractive that he could not consummate the marriage, Marillac was impressed by her gravity and dignity:[3] though he did not think her a great beauty, in his view she would be a perfectly acceptable Queen of England (she was a distant relative of both the French and English royal families), and he seems to have found Henry's attitude to her rather baffling.
Irritated by his opposition, the Guises compelled him to leave the court, and he died on 2 December of the same year, at Melun, France.