With the start of World War I, the party was divided on the issue of Russia's participation in the war. Most SR activists and leaders, particularly those remaining in Russia, chose to support the Tsarist government mobilisation against Germany. Together with the like-minded members of the Menshevik Party, they became known as "oborontsy" ("defensists"). Many younger defensists living in exile joined the French Army as Russia's closest ally in the war. A smaller group, the internationalists, which included Chernov, favoured the pursuit of peace through cooperation with socialist parties in both military blocs. This led them to participate in the Zimmerwald and Kienthal conferences with Bolshevik emigres led by Lenin. This fact was later used against Chernov and his followers by their right-wing opponents as alleged evidence of their lack of patriotism and Bolshevik sympathies.