In Western Europe, the war was largely a stalemate as a result of extensive trench warfare that gave the defenders a massive advantage during battles. In Russia, however, the monarchy was overthrown by rebels, who then negotiated peace and surrendered large chunks of land to the Germans, allowing them to concentrate all their troops and resources to the Western Front.
Despite the North's greater population, however, the South had an army almost equal in size during the first year of the war. The North had an enormous industrial advantage as well. At the beginning of the war, the Confederacy had only one-ninth the industrial capacity of the Union. But that statistic was misleading