Louis VIII of France vs Osman I

Louis VIII led a French invasion of England at the invitation of English barons rebelling against King John. He was proclaimed King of England in London but failed to consolidate control after John's death and the barons' shift of allegiance to Henry III.

Louis VIII signed the Treaty of Lambeth, formally abandoning his claim to the English throne. He renounced his invasion and received a financial settlement, ending the First Barons' War and securing peace between France and England.

Louis VIII led a royal campaign in the Albigensian Crusade against the Cathars in southern France. He captured Avignon and several strongholds, extending Capetian authority into Languedoc, but died before completing the conquest.

Osman I declared independence from the Seljuk Sultanate of Rum, establishing his own beylik (principality) in northwestern Anatolia. This act is traditionally considered the founding of the Ottoman state, which would later grow into a vast empire.

Osman I led his forces to victory against a Byzantine army at Bapheus near Nicomedia. This battle established Osman's reputation as a ghazi warrior and marked the beginning of Ottoman expansion into Byzantine territory in northwestern Anatolia.

Osman I formed a temporary alliance with the Byzantine emperor Andronikos II against the Catalan Company. This pragmatic relationship allowed Osman to gain resources and recognition while expanding his territory.

Osman I initiated the siege of the Byzantine city of Bursa, though it was captured by his son Orhan after Osman's death. The conquest of Bursa provided the Ottomans with their first major urban center and capital.