Esen Taishi vs John of Brienne

Esen Taishi led the Oirat Mongols to victory at the Battle of Tumu Fortress, capturing the Ming emperor Zhengtong. This event shocked the Ming dynasty and demonstrated Oirat military power, though Esen failed to capitalize on the victory.

Esen Taishi proclaimed himself khan of the Mongols, claiming the title of Great Khan. This move alienated many Mongol nobles and led to internal conflict, weakening his position.

Esen Taishi was assassinated by former allies, ending his rule. His death led to the decline of Oirat power and the fragmentation of the Mongol confederation.

John of Brienne was elected King of Jerusalem by the Haute Cour, marrying Maria of Montferrat, the heiress. He became king at a time when the kingdom was reduced to the coastal city of Acre and faced threats from the Ayyubids.

John of Brienne led the crusader forces in the Fifth Crusade, besieging the Egyptian city of Damietta. After a long siege, the city fell in 1219, but the crusaders failed to capitalize on the victory due to internal divisions.

John of Brienne negotiated with Ayyubid Sultan al-Kamil, who offered to return Jerusalem in exchange for the crusaders leaving Egypt. John refused, influenced by the papal legate Pelagius, leading to the eventual failure of the Fifth Crusade.

John of Brienne was elected Latin Emperor of Constantinople, ruling as regent for the young Baldwin II. He brought military experience to the beleaguered empire, which was threatened by the Byzantine Empire of Nicaea and the Second Bulgarian Empire.

John of Brienne successfully defended Constantinople against a siege by John III Vatatzes of Nicaea and Ivan Asen II of Bulgaria. His leadership preserved the Latin Empire for another generation.