The Greek 6th division attacked on 19 June from Assiros (Yuvesna) toward the direction of Lachanas and succeeded after losing some 530 men to capture the line Dichalo-Klepe. The 1st division advanced from the south and successfully captured Vertiskos. On 20 June the two Greek divisions advanced further and joined their flanks while they made contact with the main Bulgarian defensive location of Lachanas despite the fire from the Bulgarian artillery. In the night of 20–21 June the order from HQ to create a detachment to hold the forces attacking Klkis arrived and the relevant orders were given. In the morning of 21 June the Bulgarian concentrated artillery fire on the 5th regiment. Observing the IIIrd battalion withdrawing, to participate in the forming detachment for Kilkis, the Bulgarians saw an opportunity and attacked the Ist battalion forcing it to retreat with heavy losses. A counterattack with the IInd battalion led by the regiment commander stopped the Bulgarians. Following the fall of Kilkis in the morning, the order for the formation of the detachment was cancelled. At 15:00 the two Greek divisions attacked the Bulgarian position in close coordination with artillery and by 16:00 had broken the Bulgarian defence, which seemed taken aback following its morning success against the I/5. The Bulgarians retreated in disorder leaving 16 guns and 500 prisoners in the hands of the Greeks.