Joan, Countess of Ligny
Joan, Countess of Saint- Pol and Ligny( d. 18 September 1430, Avignon), called the Demoiselle de Luxembourg, was the daughter of Guy of Luxembourg, Count of Ligny and Mahaut of Châtillon, Countess of Saint- Pol.
At the death of Philip I, Duke of Brabant, she was his nearest living relative on the Saint- Pol side and inherited Saint- Pol and Ligny upon his death on 14 August 1430.
She was living at the time at Beaurevoir, which belonged to her favourite nephew John.
At this time, John held Joan of Arc, whom he had captured, as a prisoner.
The Demoiselle de Luxembourg showed kindness to her and pleaded with her nephew not to sell Joan to the English.
The Demoiselle died shortly thereafter; her fiefs were divided between her senior nephew, the Count of Brienne, who received Saint- Pol, and John, her favourite, who received Ligny.
The Demoiselle is a character in Philippa Gregory's 2011 historical novel" The Lady of the Rivers", which centres on her great- niece Jacquetta of Luxembourg.
John of Luxembourg, Lord of Beauvoir
John of Luxembourg ("Jean de Luxembourg")
(– bef.
2 July 1397, Italy), was Lord of Beauvoir (or Beaurevoir) and Richebourg, and also (as "John II")
Count of Brienne and Conversano .
He was a son of Guy I of Luxembourg, Count of Ligny and Mahaut de Châtillon (1335–1378), Countess of Saint-Pol.
John married around 1387 with Margaret, Countess of Brienne, daughter of Louis of Enghien, heiress of the counties of Brienne and of Conversano, and the Lordship of Enghien.
They had five children:
Marie of Savoy, Countess of Saint-Pol
Marie of Savoy, Countess of Saint- Pol, de Brienne, de Ligny, and Conversano( 20 March 1448 – 1475) was the second wife of Louis de Luxembourg, Count of Saint- Pol, Constable of France.
She was a younger daughter of Louis, Duke of Savoy and Anne de Lusignan, Princess of Cyprus, one of nineteen children.
Charles, Count of Maine
Charles du Maine( 1414–1472) was a French prince of blood and an advisor to Charles VII of France, his brother- in- law, during the Hundred Years' War.
He was the third son of Louis II, Duke of Anjou and King of Naples, and Yolande of Aragon.
In 1434, he married Cobella Ruffo( d. 1442), Countess of Montalto and Corigliano.
They had one son, named Jean Louis Marin, who died as an infant.
In 1437, he took up arms on behalf of King Charles VII of France, participating in the capture of Montereau, and that of Pontoise, in 1441.
At this time, his brother, René of Anjou, ceded to him the County of Maine.
He continued to take part in King Charles' campaigns.
By his second marriage, in 1443, to Isabelle of Luxembourg( d. 1472), daughter of Peter I of Luxembourg, Count of Saint- Pol, he had two children:
A dispute over the county of Guise between Charles and Isabelle's brother, Louis of Luxembourg, Count of Saint- Pol, was settled by settling it upon Isabelle as a dowry.
Charles also had an illegitimate daughter, Mary of Anjou, who married Thomas Courtenay, 6th Earl of Devon.
He led the rearguard for King Louis XI of France at the Battle of Montlhéry.
Hugh IV, Count of Saint-Pol
Hugh IV of Saint- Pol( died March 1205 in Constantinople) from the House of Campdavaine, son of Anselm of Saint- Pol, was Count of Saint- Pol from 1174 to his death, and lord of Demotika( Didymoteicho) in Thrace in 1204 – 05.
He participated in the Third and Fourth Crusades.
Margaret, Countess of Brienne
Marguerite d' Enghien, suo jure Countess of Brienne and of Conversano," suo jure" Heiress of Enghien, and Lady of Beauvois( born 1365), was a wealthy noblewoman from the County of Hainaut in her own right, having inherited the counties of Brienne and of Conversano, and the Lordship of Enghien from her father Louis of Enghien on 17 March 1394.
She was the wife of John of Luxembourg, Sire of Beauvois and the mother of Peter of Luxembourg, Count of Saint- Pol, Count of Brienne and of Conversano who inherited her fiefs, and John II of Luxembourg, Count of Ligny.
John, Count of Saint-Pol
John of Saint- Pol( died 1344) was Count of Saint- Pol between 1317 and 1344.
He was the eldest son of Guy IV, Count of Saint- Pol and Marie of Brittany.
He married in 1319 with Joanna, daughter of John I of Fiennes, and had 2 children:
Anthony I, Count of Ligny
Anthony I, Count of Ligny( 1450 – 1519) was the youngest son of Louis de Luxembourg, Count of Saint- Pol and his wife, Jeanne de Bar, Countess of Marle and Soissons.
In 1482, he inherited the County of Brienne from his brother Peter II, Count of Saint- Pol.
After the death of Charles of Bourbon in 1510, Anthony inherited the County of Ligny, which thereby fell back to the House of Luxemburg.
Marie of Luxembourg, Countess of Vendôme
Marie of Luxembourg( died 1 April 1547) was a French princess, the elder daughter and principal heiress of Peter II of Luxembourg, Count of Saint- Pol and Soissons, and Margaret of Savoy, a daughter of Louis I, Duke of Savoy.
She belonged to the French, cadet branch of a dynasty which had reigned as Dukes of Luxembourg, and whose senior line provided several Holy Roman Emperors, before becoming extinct in 1437.
Her paternal grandparents were Louis of Luxembourg, Count of Saint- Pol and Brienne and Jeanne de Bar, Countess of Marle and Soissons.
Her maternal grandparents were Louis I, Duke of Savoy and Princess Anne of Cyprus.
Peter I, Count of Saint-Pol
Peter of Luxembourg (1390 – 31 August 1433) was a son of John of Luxembourg, Lord of Beauvoir, and his wife Marguerite of Enghien.
His inheritance included the counties of Brienne, Conversano and Saint-Pol.

Question: Who is Peter I, Count Of Saint-Pol's paternal grandmother?
Answer: Mahaut de Châtillon