The First Battle of İnönü took place between 6 and 11 January 1921 near İnönü in Hüdavendigâr Vilayet during the Greco-Turkish War (1919–22), also known as the western front of the larger Turkish War of Independence. This was the first battle for the Army of the Grand National Assembly that was newly built standing army (Düzenli ordu) in place of irregular troops.

Politically, the battle was significant as the arguments within the Turkish National Movement were concluded in the favor of the institution of a centralized control of the Army of the Grand National Assembly. As a result of his performance at İnönü, Colonel İsmet was made a general. Also, the prestige gained in the aftermath of the battle helped the revolutionaries to announce the Turkish Constitution of 1921 on January 20, 1921. Internationally, the Turkish revolutionaries proved themselves as a military force. The prestige gained in the aftermath of the battle helped revolutionaries to initiate a new round of negotiations with Soviet Russia which ended with the Treaty of Moscow on March 16, 1921.