I'll give you a brief explanation. The Turkish Nationalists were a bit more than simply nationalists. Their leader, Kemal Attaturk was a General in the army and was considered to be a national hero after his actions during the Dardanelles Offensive. After the war, the military still had all the structures in place to function. Rather than building a nationalist movement from the very bottom, ie from the peasantry, this nationalist movement was built from the top of a professional and structurally sound military. Because of this, it was much easier for Ataturk to rally a force. If you want to learn more, then I suggest reading A History of the Modern Middle East by Cleveland, who has a bit on this very subject.