The battle began when the Greek army attacked the Ottoman fortified position at Yenidje (now Giannitsa, Greece), which was the last line of defense for the city of Thessaloniki.

[2] The Greek Army of Thessaly crossed into Ottoman territory in the early morning hours of 5 October, finding most border posts to be abandoned.

Upon reaching their second defensive line, the Ottomans became aware of the 4th Division's seizure of Porta Pass, panic spread in their ranks and many soldiers began fleeing and abandoning their equipment.

[5] On the morning of 10 October, the 4th Division charged down the northern slope of the Rahovo Mountain, surprising the Ottoman infantry and artillerymen who engaged in a disorganized retreat.

[9] The Ottomans fought a number of small scale delaying actions at Kolokouri, Tripotamos and Perdika, the Greek army nevertheless continued its advance taking Veroia and Katerini on 16 October.

[11][12] The Ottomans chose to organize their main defensive line at Yenidje either because of the town's religious importance for Macedonia's Muslim population or because they did not wish to fight too close to Thessaloniki.

The hill was surrounded by two rough streams, its southern approaches were covered by the swampy Giannitsa Lake while the slopes of Mount Paiko complicated any potential enveloping maneuver from the north.

The 7th Division and the cavalry brigade covered the right flank of the army by advancing towards Gida; while the Konstantinopoulos Evzone detachment was ordered to seize Trikala.

The 4th and 6th Divisions conducted a flanking maneuver from the west, in the meantime the Konstantinopoulos Evzone detachment and the cavalry brigade rushed towards Loudias; thus creating two fronts on either side of the Giannitsa Lake.

This caused the 2nd and 3rd Greek Divisions to significantly slow down their advance, however by nightfall, they managed to establish a large bridgehead across the Gramos river which flows into Giannitsa Lake from the north [12] Contrary to the orders they had received the 7th Division and the cavalry brigade encamped at Gida upon reaching it, while the Konstantinopoulos Evzone detachment likewise failed to cross the Loudias after failing to locate a bridge.

The 4th and 6th Greek Divisions progressed steadily on the western edge of the battlefield, crushing two counter-attacks and forcing the Ottomans to move their headquarters further back.

Crown Prince Constantine ordered a single regiment of the 2nd Greek Division to chase the retreating Ottomans along the road to Thessaloniki, but it proved to be too narrow for an effective pursuit.

However since the engineers of the 7th Division and the cavalry brigade failed to arrive on time, it was unable to reach the Axios and block its bridges; enabling many Ottomans to flee.

Citing Greek intelligence agents within the Bulgarian capital that the latter had taken Serres and were rapidly approaching Thessaloniki, a vexed Venizelos repeatedly urged Constantine and King George I to act.

Tahsin Pasha offered to surrender the city without a fight and in return requested that Thessaloniki's garrison could retain its weapons and retreat to Karaburnu where it was to remain until the end of the war.

Under the terms of the treaty Greece captured 26,000 men and seized 70 artillery pieces, 30 machine guns, 70,000 rifles and large amounts of ammunition and other military equipment.