The war had had a profound impact, affecting the social, political and economic systems of Europe and inflicting psychological and physical damage. Several empires collapsed: first the Russian Empire in February 1917, followed by the German Empire, Austro-Hungarian Empire and Ottoman Empire. Anti-war sentiment rose across the world; the First World War was described as "the war to end all wars", and its possible causes were vigorously investigated. The causes identified included arms races, alliances, militaristic nationalism, secret diplomacy, and the freedom of sovereign states to enter into war for their own benefit. One proposed remedy was the creation of an international organisation whose aim was to prevent future war through disarmament, open diplomacy, international co-operation, restrictions on the right to wage war, and penalties that made war unattractive.