In the post-World War I (1918) Turkey, violence and chaos were widespread in Anatolia. The long lasting war had created economic and social difficulties which in turn led to conflicts. The Sultan and Porte were in favour of reaching a peace agreement with the Allies without having another war. However, the occupation of İzmir by the Greek Forces in May 1919, led to a rise of pre-planned resistance movement which became later on the nationalist movement ‘Kuvay-ı Milliye’, in Anatolia. While the Sultan and Porte were still hoping that a peace agreement was possible with the Allies, the nationalists believed that a war with the occupiers was unavoidable, particularly with the Greek Forces. A disagreement between İstanbul and Anatolia in terms handling the occupiers gradually evolved into a Civil war between the two. The north western part of Anatolia, Düzce - Adapazarı region where mainly populated by Circassians, became the centre of the conflict between İstanbul and Ankara in May 1920. The Circassians rose against Ankara due to the impact of Ankara’s policy of establishing hegemony in the region. Interestingly, despite the fact that initially the Circassians did not act in coordination with the government in Istanbul; later on their relationship grew into an alliance. While a significant number of Circassian military officials, bureaucrats and statesmen supported Ankara government, Circassians of Düzce - Adapazarı region remained as loyal followers of the Sultan/Caliph joint to pro – İstanbul side of the Civil War. This paper will attempt to shed light to the Circassian opposition to the nationalist movement of Ankara in Düzce – Adapazarı region. It will also argue that the role of Circassians in the Civil war was neglected in the main stream historiography of Turkey due to homogenization and nation building policies of the early Turkish Republican period. Furthermore, it will also emphasize the impact of intra – Circassian conflict in the region since ironically their uprising was suppressed by a leader of Circassian irregulars, Çerkes Ethem. By using the British National Archive, the Prime Ministry Ottoman Archive, and the military archive of Turkish General Staff, this paper will demonstrate that how the Circassian mobilisation in Düzce – Adapazarı region posed a threat to the nationalist movement, when the movement was still in its infancy.