Oborin joined the Red Army in June 1918, fighting in the Russian Civil War. He fought on the Eastern Front and the Southern Front. Oborin became a gun commander of the 1st Light Artillery Battery at the headquarters of the 3rd Army's special units. From April 1919, he served in the 30th Rifle Division as a battery starshina, platoon commander, and finally assistant battery commander in the howitzer artillery battalion. In May 1919, he joined the Communist Party of the Soviet Union. From October 1920, Oborin served with the 4th Army fighting against the White Army in Crimea.