Philippe de Lorraine-Armagnac was the lover of Philippe I, Duke of Orleans, brother of the King, so called "Monsieur".

Tthis cadet of the French branch of the house of Lorraine had, by the end of the 1650s, hooked Monsieur. The young prince loved him with a passion that worried Madame Henrietta and the court bishop, Cosnac, but the King understood that, thanks to the attractive face and sharp mind of the good-looking cavalier, he would have his way with his brother.

Under these circumstances it is no surprise that Monsieur's first marriage was unhappy. In January 1670 his wife prevailed upon the King to imprison the chevalier, first near Lyon, then in the chateau d'If, and finally banish him to Rome.

But by February Monsieur's protests and pleas persuaded the King to restore him to his brother's entourage. The death of the Duchess in the following June was popularly attributed to poison, although there was little evidence for Monsieur to have perpetrated such a deed, whereas some of his mignons had earned her enmity and she theirs - and were suspected.