10 – Battle of Pelekanon (1329)
Also known as the Battle of Pelecanum, this battle marked the end of Byzantine interests in Asia. After defeats at Magnesia and Bapheus in 1302, Emperor Andronikos II tried to fight back by bolstering his army with mercenaries known as the Catalan Company. The Byzantines enjoyed brief success in 1303 as this 6,500 man army, led by Michael IX and Roger de Flor, drove the Turks back. However, it was a momentary respite, and the tide turned when de Flor was assassinated by Michael in 1305.
It was a terrible move by Michael as the Catalans started to pillage the countryside of Anatolia in revenge for the murder of their leader. They left and attacked Thrace in 1307, so the Ottomans were once again able to move back into Anatolia. The Turks continued to enjoy military success for the next couple of decades, and their cause was further helped by the Byzantine Civil War (1321- 1328).
In this war, Andronikos II was backed by Serbia while his rival, his grandson Andronikos III, was backed by the Bulgarians. Andronikos III emerged victorious in 1328, but by then, the Turks had conquered almost all Byzantine territory in Anatolia. With the help of John Cantacuzene, the new emperor summoned an army of 4,000 men and met the Turkish army of 8,000 at Pelekanon; the Ottoman army was led by Sultan Orhan I.
It was the first time that the leaders of the Byzantines and Ottomans met one another on a battlefield. Alas, the Byzantines were no match for their superior opponents and were routed. The small Byzantine army was a clear sign that the empire was no longer any threat and from that point onwards, it continued to lose what little territory it has left. It never again tried to regain territory in Asia and stumbled on for another century, a hollowed-out husk of what it once was.