In the next years, he served mainly in staff positions, and in the early phase of the First Balkan War held the post of Deputy Chief of the Hellenic Army General Staff, with responsibility for the rear areas. On 28 October 1912, he assumed command of the newly raised 7th Infantry Division guarding the demarcation line with the Bulgarian Army near Thessaloniki and the Pangaion Hills. Although allies in the war, Greece and Bulgaria were rivals over possession of Macedonia, and Sotilis forces were involved in clashes with the Bulgarians along the demarcation line. With the outbreak of the Second Balkan War between the former allies in June 1913, he led his division to victories against the Bulgarians at Sulovo, Nevrokop, Kremenska, Djumaya, and Prendel Han. On 19 July he became commander of the temporary Nevrokop Army Detachment, comprising the 7th and 8th divisions.