[9] Over the following weeks, the Greek army began expanding its zone of occupation around the city,[10] The Greek occupation immediately faced armed resistance by irregular forces, and was hampered due to political considerations: as the Smyrna Zone was still officially Ottoman territory, Turkish officials remained in place in the civil administration, as well as in the telegraph and railways; censorship was not imposed and allowed the propaganda of the Turkish National Movement to be freely distributed; and the disarming of the civilian population (including demobilized Ottoman soldiers) was prohibited by the Allies.

[12] On 12 June 1919, it was occupied by a Greek detachment of the 1st Battalion of the 8th Cretan Regiment, a mountain artillery platoon, and a half-company of cavalry, under Major Apostolos Sermakezis.

[12] On the next day, part of the detachment (110 men with a machine-gun squad[14]) was moved to the port town of Dikili, to ensure the supply of the Greek force.

[12] On the same day, Sermakezis notified his superior command in Smyrna (1st Infantry Division headquarters under Colonel Nikolaos Zafeiriou) that Turkish forces began assembling around Bergama to attack his position.

The Greek forces in the town comprised two and a half infantry companies, three machine-gun squads, two mountain guns and the cavalry half-company.

[12][13] Once this became known in Smyrna, Colonel Zafeiriou ordered the 6th Archipelago Regiment (Col. Charalambos Tseroulis) to board ship to Dikili to come to the assistance of the garrison at Bergama.

[4] As a result, Sermakezis left only a few second-line men to guard the barracks and deployed his entire remaining force to defend the perimeter around the town.

[4] The capture of Old Bergama towards the afternoon placed the Greek detachment in jeopardy, and its commander decided to withdraw under cover of night.

[4] The Greek official history claims that they faced a force about 1,000 strong with 4–6 machine guns, deployed on the heights southwest of the town.

[4] The Turks realizing that they did not possess enough men, weapons and ammunition to engage a bigger force, decided to abandon Bergama and retreat from the town.

A small Turkish force of 56 men equipped with a machine gun and commanded by lieutenant Sabri Bey, was given the task to cover the withdrawal.