The Battle of Pelekanon also known by its Latinised form Battle of Pelecanum occurred on June 10-11, 1329 between an expeditionary force by the Byzantines led by Andronicus III and an Ottoman

Ottoman Empire

The Ottoman EmpireIt was usually referred to as the "Ottoman Empire", the "Turkish Empire", the "Ottoman Caliphate" or more commonly "Turkey" by its contemporaries...

 army led by Orhan I

Orhan I

Orhan I or Orhan Bey was the second bey of the nascent Ottoman Empire from 1326 to 1359...

. The Byzantine army was defeated, with no further attempt made at relieving the cities in Anatolia

Anatolia

Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...

 under Ottoman siege.

Clash and Outcome

By the accession of Andronicus in 1328, the Imperial territories in Anatolia had dramatically shrunk from almost all of the west of modern Turkey forty years earlier to a few scattered outposts along the Aegean Sea

Aegean Sea

The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...

 and a small core province around Nicomedia

Nicomedia

Nicomedia was an ancient city in what is now Turkey, founded in 712/11 BC as a Megarian colony and was originally known as Astacus . After being destroyed by Lysimachus, it was rebuilt by Nicomedes I of Bithynia in 264 BC under the name of Nicomedia, and has ever since been one of the most...

 within about 150 km of the capital city Constantinople

Constantinople

Constantinople was the capital of the Roman, Eastern Roman, Byzantine, Latin, and Ottoman Empires. Throughout most of the Middle Ages, Constantinople was Europe's largest and wealthiest city.-Names:...

. Everywhere the Turks were hostile and encroaching on Imperial lands. Andronicus decided to relieve the important cities of Nicomedia and Nicaea and hopefully restore the frontier to a stable position.
Together with the Grand Domestic John Cantacuzene

John VI Kantakouzenos

John VI Kantakouzenos or Cantacuzenus was the Byzantine emperor from 1347 to 1354.-Early life:Born in Constantinople, John Kantakouzenos was the son of a Michael Kantakouzenos, governor of the Morea. Through his mother Theodora Palaiologina Angelina, he was a descendant of the reigning house of...

, Andronicus led the army, which was the greatest he could muster along the Sea of Marmara

Sea of Marmara

The Sea of Marmara , also known as the Sea of Marmora or the Marmara Sea, and in the context of classical antiquity as the Propontis , is the inland sea that connects the Black Sea to the Aegean Sea, thus separating Turkey's Asian and European parts. The Bosphorus strait connects it to the Black...

 towards Nicomedia. At Pelekanon, an Ottoman Turkish army blocked their way. Parts of each army clashed and the Turks were driven off. However, the bulk of the Turkish army withdrew into the hills north of the battlefield and Andronicus could advance no further while it was intact. Further skirmishes resulted in the emperor sustaining light wounds while morale plummeted. When the Turks occupied the roadway behind them, the Grand Domestic arranged for the army to return to Constantinople by sea.

Consequences

A campaign of restoration was aborted. Never again did a Byzantine army attempt to regain any Asian territory. The historic former capitals of Nicomedia and Nicaea were not relieved and the maintenance of Imperial control across the Bosphorus was no longer tenable. The Ottomans built up a strong base from which they eventually swept away the Byzantine Empire as a whole.