John of Brienne vs Xiao Xi

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.

Xiao Xi declared himself emperor of the Liang dynasty in Jiangling, claiming legitimacy as a successor to the Southern Liang. He established a court and ruled over a small territory in the south.

Xiao Xi's Liang forces were defeated by the Tang general Li Xiaogong. The defeat led to the collapse of the Liang dynasty and Xiao Xi's capture.

Xiao Xi was executed by the Tang dynasty after his capture. His death ended the Liang pretender state and furthered Tang consolidation of the south.