World War I is one of the deadliest conflicts in history, with an estimated 9 million people killed in combat and more than 5 million civilians killed in military occupation, bombing, starvation and disease. Millions of people died as a result of the Armenian genocide in the Ottoman Empire and the 1918 flu pandemic. I must say that, despite a huge amount of research (by the end of 2012, about 60,000 works on the First World War were published in the world), the question of the prerequisites and causes of this war is still one of the most controversial. Historians do not stop arguing about the causes of the war, about the degree of readiness of the participating countries for it, about responsibility for unleashing the conflict. Each side puts the blame on the enemy. Why did this terrible event happen at the beginning of the twentieth century? What were the deep reasons for the beginning of the conflict? What consequences did it cause? Read about this and much more in the new book of the series "Complete History of Eras."