[December 24] John I, count of Hainaut

Parents: Bouchard IV, lord of Avensnes, and Margaret II, countess of Flanders
Date of Birth: 1 May 1218
House: Avesnes
Spouse(s): Adelaide, daughter of Floris IV, count of Holland, and Matilda of Brabant
Predecessor: Margaret II
Reign: 1246 – 1257
Brief: The legitimate, though declared illegitimate, son of the countess of Flanders, John fought an uphill battle much of his life to achieve Imperial legitimacy for his claim to Hainaut. When Margaret produced a son, William, with her second husband in 1244, proclaiming him her heir, John and his brother, Baldwin, declared war, sparking the War of the Succession of Flanders & Hainaut. The conflict only ended in 1246 when King Louis IX of France forced a settlement. The inheritance was split, with John gaining Hainaut and William, Flanders. But Margaret would not relinquish her control over Hainaut, and John paid for the assassination of William as revenge in 1251. Another son, Guy, continued William's claim and the war restarted, ending in 1253 with the defeat of the Flanders faction at the Battle of West-Capelle. Margaret decided to sell her rights to Charles, duke of Anjou, rather than give them to John, but John's brother-in-law was the German king and fought against Charles to secure John's succession. John only briefly held Hainaut undisputedly, dying in late 1257, only a month after the final settlement. His son inherited both Hainaut and Holland and continued fighting to gain Flanders as well.

Date of Death: 24 December 1257

Successor: John II

Other Monarchs Who Died Today:

• Sisinnius I, archbishop of Constantinople (427)
• Go-Sakuramachi, empress of Japan (1813)
• Duarte II, pretender to Portugal (1976)