Army invaded Transylvania and had initial successes, but was forced to stop and was pushed back by the Germans and Austro-Hungarians when Bulgaria attacked them from the south. Meanwhile, a revolution occurred in Russia in March 1917 (one of the causes being the hardships of the war). Tsar Nicholas II was forced to abdicate and a Russian Provisional Government was founded, with Georgy Lvov as its first leader, who was eventually replaced by Alexander Kerensky. The newly formed Russian Republic continued to fight the war alongside Romania and the rest of the Entente in desultory fashion. It was overthrown by the Bolsheviks in November 1917. Following the Armistice of Focșani between Romania and the Central Powers, Romania also signed a peace treaty with the Central Powers on 7 May 1918, however it was canceled by Romania on 10 November 1918. The new government established by the Bolsheviks signed the Treaty of Brest-Litovsk with the Central Powers in March 1918, taking it out of the war; leading to Central Powers victory in the Eastern Front and Russian defeat in World War I. Geography The front in the east was much longer than that in the west. The theater of war was roughly delimited by the Baltic Sea in the west and Minsk in the east, and Saint Petersburg in the north and the Black Sea in the south, a distance of more than . This had a drastic effect on the nature of the warfare. While the war on the Western Front developed into trench warfare, the battle lines on the Eastern Front were much more fluid and trenches never truly developed. This was because the greater length of the front ensured that the density of soldiers in the line was lower so the line was easier to break. Once broken, the sparse communication networks made it difficult for the defender to rush reinforcements to the rupture in the line, mounting rapid counteroffensives to seal off any breakthrough. Propaganda Propaganda was a key component of the culture of World War I. It was often shown through state-controlled media, and helped to bolster nationalism and patriotism within countries. On the Eastern Front, propaganda took many forms such as opera, film, spy fiction, theater, spectacle, war novels and graphic art. Across the Eastern Front the amount of propaganda used in each country varied from state to state. Propaganda took many forms within each