Semyon Timoshenko was born into a poor family in 1895 in modern day Ukraine. He was drafted into the Russian Army in 1915 and sided with the communists during the Russian Revolution in 1917. During the Civil War, he met with Joseph Stalin. This meeting helped him workhis way up in the army during the reign of Stalin. He was assigned as a Commander in various different parts of Russia. He was sent to the front lines to fight back against the Germans during Operation Barbarossa and was later sent to Ukraine to fight against a German offensive which ultimately failed.
Though Timoshenko received the blame, it is argued that he received little support from Stalin in order to fight back. He was then moved back to Leningrad and replaced by Zhukov. After the war, he served in many various different military roles in the Soviet Unionuntil his death in 1970.
Information from 2DB.