Jean I d'Avesnes, count of Hainault

https://nl.wikipedia.org/wiki/Huis_Avesnes

John I, Count of Hainaut

John of Avesnes (1 May 1218 – 24 December 1257) was the count of Hainaut from 1246 to his death.

Family

From http://genealogics.org/getperson.php?personID=I00012262&tree=LEO

• Father Bouchard IV of Avesnes
• Mother Margaret II of Flanders
• Spouse(s) Adelaide of Holland, NN Issue by his wife
• John II, Count of Hainaut and Holland
• Baldwin of Hainaut
• Joanna, Abbess of Flines
• Bouchard, Bishop of Metz
• Guy of Avesnes
• William, Bishop of Cambrai
• Florent of Hainaut

Issue by his mistress

• Marguerite d'Avesnes

Biography

From https://en.m.wikipedia.org/wiki/John_I,_Count_of_Hainaut

Jan was born in Houffalize on 1 May 1218, the son of Bouchard d'Avesnes and Margarethe, countess of Flanders and Hainault, the daughter of Baudouin VI-IX, count of Flanders, emperor of Constantinople. As the marriage of Margarethe and Bouchard was dissolved by the pope in 1221, he and his younger brother Baudouin were considered illegitimate (an elder brother Baudouin had died in infancy).

In 1223 Jan's mother married Guillaume de Dampierre and bore more children who could claim her inheritance. Thus Jan and his brother Baudouin undertook to receive imperial recognition of their legitimacy and did so from Emperor Friedrich II in March 1243. On 5 December 1244 Margarethe inherited Flanders and Hainault and designated her eldest son by her second husband, Guillaume III de Dampierre, as her heir. Immediately a war, called the War of the Succession of Flanders and Hainault, started over the rights of inheritance, pitting Jan against Guillaume.

After two years of fighting, in 1246 Louis IX of France intervened to settle the conflict. He granted Hainault to Jan and Flanders to Guillaume. Nonetheless, conflict was reopened. Meanwhile, in September 1246 Jan married Aleida of Holland, daughter of Floris IV, count of Holland and Machteld of Brabant, and sister of Willem II, count of Holland. Jan and Aleida had seven children, of whom four sons had progeny: Jan II, Bouchard, Guy and Floris.

In 1250 Margarethe was forced to give over the government of Hainault to Jan. On 6 June 1251 Guillaume de Dampierre was assassinated at a joust and it was claimed that the Avesnes brothers had financed the crime. On 4 July 1253 Jan defeated the armies of his mother Margarethe and her second Dampierre son Guy at the battle of West-Capelle. Guy was imprisoned and Margarethe agreed to sell her rights to Hainault to Charles I Etienne, brother of Louis IX, if he would reconquer it from Jan. Jan's brother-in-law Willem II, count of Holland, the emperor-elect, was convinced to grant Hainault (an imperial fief) and those Flemish lands within the empire to Jan. Charles was defeated, and under the terms of the Treaty of Péronne of 1256 King Louis, returning from the Seventh Crusade, ordered his brother to abide by his arbitration of 1246. On 22 November 1257 Guy de Dampierre finally relinquished his claim to Hainault, but Jan died on Christmas Eve 1257 in Valenciennes. He was succeeded by his son Jan II.