In 1821 , during the last major Ottoman-Persian War , the Ottomans were crushingly defeated at Erzurum despite a numerical superiority by the Iranian Qajars at the Battle of Erzurum ( 1821 ) . In 1829 the city was captured by the Russian Empire , but was returned to the Ottoman Empire under the Treaty of Adrianople ( Edirne ) , in September of the same year . During the Crimean war Russian forces approached Erzurum , but did not attack it because of insufficient forces and the continuing Russian siege of Kars . The city was unsuccessfully attacked ( Battle of Erzurum ( 1877 ) ) by a Russian army in the Russo-Turkish War of 1877 – 78 . However , in February 1878 , the Russians took Erzurum without resistance , but it was again returned to the Ottoman Empire , this time under the Treaty of San Stefano . There were massacres of the city 's Armenian citizens during the Hamidian massacres ( 1894 – 1896 ) . The city was the location of one of the key battles in the Caucasus Campaign of World War I between the armies of the Ottoman and Russian Empires . This resulted in the capture of Erzurum by Russian forces under the command of Grand Duke Nicholas and Nikolai Nikolaevich Yudenich on February 16 , 1916 . Erzurum reverted to Ottoman control after the signing of the Treaty of Brest-Litovsk in March 1918 . In 1919 , Mustafa Kemal Atatürk , one of the key founders of the modern Turkish Republic , resigned from the Ottoman Army in Erzurum and was declared an " Honorary Native " and freeman of the city , which issued him his first citizenship registration and certificate ( Nüfus Cuzdanı ) of the new Turkish Republic . The Erzurum Congress of 1919 was one of the starting points of the Turkish War of Independence . Erzurum , known as " The Rock " in NATO code , served as NATO 's southeastern-most air force post during the Cold War
Hamidian massacres
Hamidian massacres
Erzurum