Marguerite de Bourgogne
Marguerite of Burgundy (1290 - 1315) married her cousin, Prince Louis of France in 1305. Louis, the eldest son of King Philippe IV (the fair) was King of Navarre (through his mother) and heir to the French throne (he became King Louis X of France in 1314).
Marguerite and Louis had only 1 daughter (Jeanne) after 10 years of marriage. In the book (I am not sure about the movie) Queen Isabelle of England (wife of King Edward II of England, daughter of Philippe IV of France, sister to Louis, Philippe and Charles) made a trap for her sisters-in-law Marguerite, Joanne, and Blanche, so that they could be caught in adultery. She sent them gold wallets and they gave them to their lovers. Isabelle then traveled to France to make sure of her suspicions, and after spotting the wallets on 2 of the court men, she told her father, the King, of the adultery of the Princesses.
The Princess’s lovers were executed (by most brutal ways). The Princesses had to go through the public trial, were made (Marguerite and Blanche) nuns and were sentenced to life imprisonment.
Once the fact of her adultery was emerged, people started talking that the only daughter of Marguerite and Louis, Jeanne, was illegitimate. Indeed, Louis and Marguerite were married for 6 years and were childless and Jeanne was born after Marguerite started her affair. Little Jeanne could be both Louis’s and Marguerite’s lover’s daughter. Since it was essential for the heir to the throne to remarry, Marguerite (according to the book, I didn’t find historic evidence that it’s true, though I find it highly probable) was offered to acknowledge that her daughter was not Louis’s daughter, that she was unfaithful and “bad” wife for Louis (this would be a good enough reason for the Pope to grant the divorce). Again according to the book, Marguerite did sign under that paper but due to some circumstances the King (King Philippe had already died then, so her husband, Louis X was the King) did not receive it.
Since he was desperate to marry, not under his orders but under his silent agreement, Marguerite was allegedly strangled in 1315, after 2 years of imprisonment Note, allegedly, since it was never proved. She might have as well died of natural causes (Marguerite and Blanche were imprisoned in the same prison, Château-Gaillard, and lived in extreme condition, deprived of almost everything).
I would also like to note that though the book leaves no doubt that Marguerite and Blanche did have lovers, some historians question the value of the confession of the Princess’s lovers (Philippe and Gautier d’Aunai), since the method of procuring such confessions are well known and not exactly appropriate.
King Louis married Clemence of Hungary in 1315. He died in 1316, leaving his wife in last months of pregnancy. Clemence gave birth to a son, John the Posthumous, died only after 4 days of life.
Now, again according to the book, King Louis’s brother, Prince Philippe (King Philippe V the Tall), along with Duchess Margo (mother to Blanche and Jeanne) murdered the little King. However the story goes on to tell that the little King’s nanny, swapped him for her son (request of one of the governors, who feared for the King’s life), so the child that died, wasn’t the king at all. While one can accept the possibility that Philippe might have wanted the little King’s death but the rest is pure fiction. Though there was indeed evidence in the medieval history that a certain Italian claimed to be John the Posthumous but he never managed to prove that.
Marguerite and Louis’s daughter, Joanne, was proclaimed (not officially) a bastard. And anyway, Philippe used the ancient Salic law that prohibited women to succeed to the throne. There was a peculiarity though. Jeanne was made Queen of Navarre, which technically acknowledged that she was Louis’s daughter.