The First World War has been considered by many historians as the true dividing line of 20th century European history, the traumatic break with the dominant politics of the time.
Communism and Fascism, which grew from this war, became first alternatives and then poles attracting intellectuals, vehicles for mass politics, seed-beds for new leaders who, coming as they did from outside the old monarchical and imperial order, proposed radical breaks with the past.
The destruction and millions of deaths caused by the Firrst World War, the changes to frontiers, the impact of the Russian Revolution and the problems of adaptation faced by millions of former combatants, are at the heart of the violence  and culture of confrontation that were then established in many societies of that tumultuous period.