Lenin was in Galicia when the First World War broke out. The war pitted the Russian Empire against the Austro-Hungarian Empire, and due to his Russian citizenship, Lenin was arrested and briefly imprisoned until his anti-Tsarist credentials were explained. Lenin and his wife returned to Bern, before relocating to Zürich in February 1916. Lenin was angry that the German Social-Democratic Party was supporting the German war effort, which was a direct contravention of the Second International's Stuttgart resolution that socialist parties would oppose the conflict, and saw the Second International as defunct. He attended the Zimmerwald Conference in September 1915 and the Kienthal Conference in April 1916, urging socialists across the continent to convert the "imperialist war" into a continent-wide "civil war" with the proletariat pitted against the bourgeoisie and aristocracy. In July 1916, Lenin's mother died, but he was unable to attend her funeral. Her death deeply affected him, and he became depressed, fearing that he too would die before seeing the proletarian revolution.