The Army of Thessaly crossed into Ottoman territory in the early morning hours of 5 October, finding most border posts to be abandoned. The first major clashes took place the following day when the 1st and 2nd Greek Divisions attacked Elassona, resulting in an Ottoman withdrawal towards Sarandaporo. At 7 a.m. on 9 October, the Greek infantry began its assault on Sarandaporo. The 1st, 2nd and 3rd Divisions attacked the Ottoman main line frontally. In the meantime, the cavalry brigade, 4th and 5th Divisions conducted a flanking maneuver from the west with the intention of striking the rear of the Ottoman positions. Despite being perceived as impregnable by its defenders, the main body of the Greek forces managed to advance deep inside the pass, while auxiliary units broke through the Ottoman flanks. The Ottomans abandoned their defensive line during the night, fearing encirclement.