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|Service/branch||Russian Imperial Army,
|Commands held||30th army corps,
World War I (Romanian campaign)
Russian Civil War
Andrei Medardovich Zayonchkovski or Zaionchkovski (Russian: Андре́й Меда́рдович Зайончко́вский) (December 20 [O.S. December 8] 1862 - March 22, 1926) commanded the defence of the Romanian-Bulgarian border in Dobruja upon Romania's entry into World War I in August 1916.
After graduation from the Nicholas School of Military Engineering (Nikolaevskoe Inzhenernoe Uchilishche) in 1882, Zayonchkovski served in the 5th Sapper Battalion. In 1888 he graduated from the General Staff Academy and served in various staff positions.
During the Russo-Japanese War he commanded the 85th Vyborg Infantry Regiment and the 2nd brigade of the 3rd Siberian Infantry Division.
During World War I Zayonchkovski commanded first the 30th Army Corps. Following Romania's entry into the war on 27 August 1916, he commanded the Russian-Romanian Dobruja Army in charge of defending Dobruja against the Central Powers. He was relieved by general Dmitry Shcherbachev in April 1917 and was in retirement by the time of the October Revolution.
In 1918 he joined the Red Army, serving in various staff positions. After the end of the Russian Civil War he switched to teaching in the Red Army Military Academy and writing. He wrote a two-volume overview of World War I military operations.