Semyon Moiseevich Krivoshein (; November 28, 1899 in Voronezh, Russian Empire – September 16, 1978 in Moscow, Soviet Union) was a Soviet tank commander, who played a vital part in the World War II reform of the Red Army tank forces and in the momentous clash between German and Soviet tanks in the Battle of Kursk. Early life and Russian Civil War Krivoshein was born into the well-to-do family of a Jewish artisan shop owner and in 1917 graduated from a gymnasium, a Russian secondary school for the educated elite. In 1918 he enlisted in the Red Army to fight against the Whites in the Russian Civil War, seeing service in the 1st Cavalry Army of Semyon Budyonny. Tank commander in Spain and Siberia After the end of the war in 1921, Krivoshein stayed in the army. With the introduction in the Red Army of tank forces, Krivoshein was chosen among most talented cavalry officers to master the new brand of weapon. He was sent to study in the elite Frunze Military Academy, graduated in 1931 and served in the mechanized troops, rising in 1934 to commander of mechanized regiment. In 1936 he volunteered to fight in Spain on the side of the Republicans against nationalist General Francisco Franco, who was supported in Spain's civil war by both Fascist Italy and Nazi Germany. Krivoshein received the honor of becoming the first Soviet tank commander in Spain following his arrival alongside a small group of other Soviet volunteers and T-26 light tanks at the Republican port of Cartagena in October 1936. In November–December 1936, he commanded tank forces of the Republican army in the Battle of Madrid and won praise for his performance. While the small tank force of a single brigade could not halt Franco's offence, his bold actions bolstered the morale of the Republicans. In January 1937 Krivoshein was recalled to the Soviet Union to recuperate. He was promoted to kombrig and appointed commander of a mechanized brigade. In the summer of 1938, he led his brigade against the Japanese in the Battle of Lake Khasan. Second World War September 1939-1940: war against Poland and attack on Finland Following the conclusion of the Molotov-Ribbentrop Pact in August 1939, Germany and the Soviet Union invaded the Polish republic together. (Stalin's negotiations about non-aggression and a mutual diplomatic understanding between Germany and the USSR had tacitly aimed at retaking what had