One he went to Salonika secretly through Egypt and Greece and opened a branch of Native land and Freedom Community there, and returned to Damascus again. He stayed in Damascus for some additional time. He became Senior captain on 20 June 1907 and was commissioned with a task in the General Staff of Army in Damascus.
Mustafa Kemal was appointed to 3rd Army Headquarters in Manastır on 13 October 1907. He went to Salonika to work in a branch of this Headquarters in Salonika. İttihat ve Terakki Organization, which took the members of Vatan ve Hürriyet Organization was also in progress there. Mustafa Kemal, entering this organization, began to serve in this organization after his going to Salonika. His primary thoughts were to save the country from despotism and innovations. After a short time pursuant to his arrival in Salonika, he was given the post of railroad inspector between Uskup and Salonika on 22 June 1908, in addition to his duty in 3rd Army Headquarters.
At the same time, İttihat ve Terakki Organization, operated in Rumeli, was forcing Abdulhamit the Second to put 1876 Constitution into effect again and call Parliament of Deputies for assembly. Such initiatives of İttihat ve Terakki at last launched the era of declaration of 2nd Constitutional Monarchy.
When 2nd Constitutional Monarchy period was proclaimed, Mustafa Kemal pasha was a captain in Salonika carrying on his military task and closely monitoring the political developments in Istanbul working within the İttihat ve Terakki Organization. He did not consider works carried out pursuant to a revolution like 2nd Constitutional Monarchy and believed that more radical and greater modifications had to be made in this country taking advantage of this great opportunity. But his ideas were not in accordance with the official ideas of İttihat ve Terakki, but he did not refrain from expressing his ideas before leading persons.
It was only a year after proclamation of 2nd Constitutional Monarchy when a rebellion took place in Istanbul on 13 April 1909. Mustafa Kemal was appointed as the Chief of Staff of Movement Army, formed in Thrace to supress this rebellion known as 31 Mart Vakası (31 March Event) in history, and this army arrived in Istanbul on 19 April 1909. He perfomed important services either in marching and management of Movement Army in both Istanbul and on the way, as chief of staff.
In 1911 March, a rebellion occurred in Albania. He took part in the operation arranged to put an end to this rebellion beside War Minister Mahmut Şevket Pasha. Mustafa Kemal was dismissed from his duty in 3rd Army Headquarters on 15 January 1911 and was commissioned in the headquarters of 5th Army Corps and then in 38th Infantryman Regiment in Salonika.