Complex sentence: At the outbreak of the Russian Civil War, Tyumen was controlled by forces loyal to Admiral Alexander Kolchak and his Siberian White Army; however, the city fell to the Red Army on January 5,1918.
Split into simpler sentences: At the outbreak of the Russian Civil War, Tyumen was controlled by forces loyal to Admiral Alexander Kolchak and his Siberian White Army. However, the city fell to the Red Army on January 5,1918.