From c. 1315 on, the Latin Principality of Achaea, which controlled most of the Morea (Peloponnese) peninsula in southern Greece, entered a period of instability, as the princely title was disputed by multiple claimants.

A Catalan invasion in 1315 in support of the claims of Isabella of Sabran was defeated at the Battle of Manolada in 1316, but Prince Louis of Burgundy died soon after, leaving his title contested between his wife, Matilda of Hainaut, the Angevins of Naples, who as the Principality's liege lords forced her to marry the Angevin John of Gravina, and Louis' brother Odo IV, Duke of Burgundy.

[4] Learning of the Latins' approach, Asen intensified the siege, and on 9 September, its Greek castellan, Nicoloucho of Patras, surrendered.

The ruse succeeded, and as the Achaean army approached the castle in the belief that it was still held by their allies and that the Byzantines had abandoned the siege, Asen sprang his trap.

[4][5] In the same campaign – the Aragonese and French versions disagree on whether this happened before or after the siege of Saint George[7] – the Byzantines went on to secure, by bribing their commandants, the castles of Karytaina, Akova, and Polyphengos.

[11] During the same time, John of Gravina began preparing an expedition to the Morea, but it was not until January 1325 that the Prince of Achaea left Italy for his principality, with 25 galleys, 400 cavalry, and 1,000 infantry.