[1][2] That autumn, Boniface campaigned south into Greece, where he defeated the local magnate Leo Sgouros and drove him back to his strongholds of Nauplia and Acrocorinth in the northeastern Morea (Peloponnese), which were besieged by the Crusaders.

[5][6] Boniface sought to retain him in his own service, but Villehardouin teamed up with his fellow Champenois, William of Champlitte, whom he enticed with tales of the richness of the land and with a pledge to recognize him as his lord.

[5][7] The towns of Patras and Andravida in the northwest fell without struggle, and at the latter Champlitte received the homage of the local magnates and people of the Skorta and Mesarea in the central Morea.

They repaired the fortress walls, long ago torn down by the Venetians to stop its use as a pirate base, and assaulted the nearby fort of Coron, which fell after a single day, and the town of Kalamata, which surrendered.

[21][22] Efforts have been made to identify the locality, with some linking it with the modern village of Kapsia west of Mantinea in Arcadia, but this is too far from the reported area of the battle based on the sources, and furthermore olive trees do not grow in the region.

[22] The Battle of the Olive Grove of Kountouras was decisive for the conquest of the Morea by the Franks, as it represented the last general effort of the local Greeks to resist.

The northeast belonged to the Duchy of Athens under the suzerainty of Boniface of Montferrat, although Leo Sgouros and his men still held out in their two fortresses; and Laconia and the mountainous areas of the Taygetos and of Tsakonia remained still unsubdued.

Nevertheless, the first stage of the Frankish conquest was complete, establishing a new Crusader state, the Principality of Achaea, and in a letter of Pope Innocent III on 19 November 1205, Champlitte is styled princeps totius Achaiae provincie.