The Army of Thessaly crossed into Ottoman territory in the early morning hours of 5 October, finding most border posts to be abandoned, with the garrisons at Melouna Pass, Profitis Ilias and Tsouka resisting for several hours before retreating. The first major clashes took place the following day when the 1st and 2nd Greek Divisions attacked hastily organized defenses north of Elassona. Elassona was defended by three infantry battalions, two artillery batteries and half a squadron of cavalry. The battle for Elassona lasted for three hours, with the Ottomans retreating to avoid encirclement, thus giving the troops manning the main defensive line at Sarantaporo additional time to reinforce their positions. The Greeks went on to advance into the Elassona plateau without encountering any resistance. Between 7 and 8 October, Greek troops regrouped in front of Sarantaporo and dispatched cavalry reconnaissance patrols towards the Ottoman positions, locating the headquarters of the Ottoman VIII Corps at Hania Viglas and those of a reserve division at Glikovo.