The Army of Thessaly (Greek: Στρατιά Θεσσαλίας) was a field army of Greece, activated in Thessaly during the Greco-Turkish War of 1897 and the First Balkan War in 1912, both times against the Ottoman Empire and commanded by Crown Prince Constantine.
On 25 March, Crown Prince Constantine was named commander-in-chief of the Army of Thessaly, comprising these two divisions and support units, with Colonel Konstantinos Sapountzakis as his chief of staff.
As war with the Ottoman Empire increasingly became a possibility in the early autumn of 1912, the bulk of the Hellenic Army was gathered in Thessaly, once again under Crown Prince Constantine, comprising the four peacetime infantry divisions and three newly formed from reservists, a cavalry brigade, and auxiliary units, for a total of some 100,000 men, of which ca.
In the course of the First Balkan War, the Army of Thessaly overcame the fortified Ottoman positions along the border in the Battle of Sarantaporo and advanced north.
Despite a setback of a detached division in the Battle of Sorovich, the main army broke through the Ottoman defences at the Battle of Yenidje, forcing, after a few days, the surrender of Thessaloniki and its garrison.