During the Hungarian Revolution of 1848, the HDF drove Habsburg forces from the country in the Spring Campaign of 1849, but was defeated by an Austro-Russian offensive in the summer. The Royal Hungarian Honvéd was established in 1868. During World War I out of the eight million men mobilized by Austria-Hungary, over one million died. Conscription was introduced on a national basis in 1939. The peacetime strength of the Royal Hungarian Army grew to 80,000 men organized into seven corps commands. During World War II the Hungarian Second Army was destroyed on the banks of the Don River in December 1942 in the Battle of Stalingrad. During the Socialist and the Warsaw Pact era (1947–1989), the entire 200,000 strong Southern Group of Forces was garrisoned in Hungary, complete with artillery, tank regiments, air force and missile troops with nuclear weapons.