The Battle of the Sakarya (Turkish: Sakarya Meydan Muharebesi, lit. 'Sakarya Field Battle'), also known as the Battle of the Sangarios (Greek: Μάχη του Σαγγαρίου, romanized: Máchi tou Sangaríou), was an important engagement in the Greco-Turkish War (1919–1922).
The battle went on for 21 days from August 23 to September 13, 1921, close to the banks of the Sakarya River in the immediate vicinity of Polatlı, which is today a district of the Ankara Province. The battle line stretched over 62 miles (100 km).