Why are the years 1914-1991 sometimes referred to as "the short twentieth century?"

Why is Bismarck's reputation as a national leader higher than that of William II?

Why did European nations feel the need to create military alliances?

Which nation bears the greatest responsibility for the outbreak of World War I? How would you rank them in terms of their "guilt"?

Why were citizens willing to die for their respective countries in such large numbers?

Why did the major combatant nations feel obliged to use propaganda directed toward their own citizens in order to justify the war?