On 28 April the sultan raised 4,000 soldiers known as the Kuva-yi İnzibatiye (Caliphate Army) to combat the nationalists. Then using money from the Allies, another force about 2,000 strong from non-Muslim inhabitants were initially deployed in İznik. The sultan's government sent the forces under the name of the caliphate army to the revolutionaries to arouse counterrevolutionary sympathy. The British, being skeptical of how formidable these insurgents were, decided to use irregular power to counteract the revolutionaries. The nationalist forces were distributed all around Turkey, so many smaller units were dispatched to face them. In İzmit there were two battalions of the British army. These units were to be used to rout the partisans under the command of Ali Fuat and Refet Pasha.

Anatolia had many competing forces on its soil: British battalions, nationalist militia (Kuva-yi Milliye), the sultan's army (Kuva-yi İnzibatiye), and Ahmet Anzavur's forces. On 13 April 1920, an uprising supported by Anzavur against the GNA occurred at Düzce as a direct consequence of the fatwa. Within days the rebellion spread to Bolu and Gerede. The movement engulfed northwestern Anatolia for about a month. On 14 June, Kuva-yi Milliye faced fought a pitched battle near İzmit against the Kuva-yi İnzibatiye, Anzavur's bands, and British units. Yet under heavy attack some of the Kuva-yi İnzibatiye deserted and joined the nationalist militia. This revealed the sultan did not have the unwavering support of his own men. Meanwhile, the rest of these forces withdrew behind the British lines which held their position.

The clash outside İzmit brought serious consequences. British forces conducted combat operations on the nationalists and the Royal Air Force carried out aerial bombardments against the positions, which forced nationalist forces to temporarily retreat to more secure missions. The British commander in Turkey asked for reinforcements. This led to a study to determine what would be required to defeat the Turkish nationalists. The report, signed by French Field Marshal Ferdinand Foch, concluded that 27 divisions were necessary, but the British army did not have 27 divisions to spare. Also, a deployment of this size could have disastrous political consequences back home. World War I had just ended, and the British public would not support another lengthy and costly expedition. The British accepted the fact that a nationalist movement could not be defeated without deployment of consistent and well-trained forces. On 25 June, the forces originating from Kuva-i İnzibatiye were dismantled under British supervision. The British realised that the best option to overcome these Turkish nationalists was to use a force that was battle-tested and fierce enough to fight the Turks on their own soil. The British had to look no further than Turkey's neighbor: Greece.