Chancellor of exchequer since 1906; against his earlier inclinations, in 1914 he became a leading proponent of military action against Germany. Photograph: Hulton Archive/Getty Images/Hulton Archive/Getty Images
Wilhelm's cousin-in-law and ruler of Russia since 1894; caught between Russia's loyalty to Serbia and his desire to avoid a Europe-wide war. Photograph: Corbis/Corbis
Nephew of Austria's emperor Francis Joseph; keen to strengthen Austrian army but wary of antagonising Serbia. Photograph: Bettmann/Corbis
Liberal prime minister from 1908. Proved increasingly unpopular for his handling of the war; replaced by Lloyd George in December 1916. Photograph: Hulton-Deutsch Collection/Corbis
Foreign secretary from 1905 to 1916; was ineffective in his attempts to warn Germany against threatening Belgium's neutrality in 1914. Photograph: Time Life Pictures/Getty