Unlike the Western Front, the Eastern Front between Russia on the one side and Germany and Austria-Hungary on the other was not a static affair, with the front shifting great distances during the war. At the beginning of the First World War, Russia was quick to invade East Prussia with two armies. Germany crushed these armies at the Battle of Tannenberg and the Battle of the Masurian Lakes. Russia did have some success in 1914 against Austria-Hungary on this front, however. In 1915 Germany and Austria-Hungary made great advances, pushing the front as much as 200 miles to the East. In 1916, Russian General Aleksei Brusilov counterattacked and made some progress butdid not achieve a decisive victory. Also in 1916, Romania entered the war on Russia's side but was quickly pushed back. In 1917, the Russian Revolution occurred. While the provisional government installed in March attempted to continue the war, Russian troops lost interest in fighting and deserted in great numbers. After the October Revolution in November, Vladimir Lenin entered into an armistice with the Central Powers. With the Treaty of Brest-Litovsk in 1918, Russia gave up enormous amounts of land, although after the collapse of Germany later on in the year Russia renounced the treaty and re-occupied much of that land, although not Finland or Poland.