The invasion of İzmir and the Allied occupation of Istanbul were catalysts that drove the Turks to resistance. Immediately after the armistice, Turks had done little to oppose the Allies. Allied ‘control officers’ moved through Northern and Western Anatolia gathering weapons and asserting Allied authority. Allied ‘relief officers’ seized houses that had been occupied by Turkish refugees from the Balkans and gave them to Greek refugees returning to Anatolia. Allied officers in many, although not all, regions remarked on the cooperation shown them by local officials. With the İzmir occupation, all that changed. The mass of the Turks saw that the Allies, the sponsors of the Greeks, were the enemy. Those who still wished to cooperate with the Allies found it impossible, even dangerous, to defy the populace.

The Turkish Nationalist forces under Mustafa Kemal organised their forces politically and militarily. Mustafa Kemal managed to bring together, under the aegis of the Ankara Grand National Assembly, a disparate group of Ottoman politicians who had fled Istanbul, army officers, local armed bands who had opposed the Greeks and Armenians, and religious leaders.

The Ottoman army in Syria, though defeated, had retired intact, led by Mustafa Kemal Paşa. The army in the Northeast had retreated to the 1914 borders, also intact. Both had suffered desertions, but many of the deserters returned to the Nationalist colours. The Nationalists began military organisation and trained new recruits. What had begun as a political movement now was an army.

The Nationalist army was not ill-equipped. Under the terms of the Mudros Armistice, the Allies were to collect the weapons of demobilised Ottoman army units. They had begun to do so in Western Anatolia and Thrace, but had not yet been able to seize the military supplies in other parts of Anatolia when the İzmir invasion halted Turkish cooperation. And the sequestered weapons in regions of Allied control began to disappear, sent secretly to the Nationalists by sympathisers in the Istanbul Government and army. When the Nationalists raided an arms dump at Gallipoli, 80,000 rifles were taken.