Why Did the First World War Break Out in August 1914?

The First World War broke out because of a system of two major European Alliances. These started a war due to Germany's ruthlessness, and caused a European war. Then the nations' colonies joined in, and eventually all of the world's major powers had joined in, causing the First World War.
Before the main events of the war, two main alliances had been formed. Germany had defeated France in the Franco-Prussian war in 1871. 3 000 French soldiers were killed, 14 000 wounded, and about 100 000 captured. Most importantly, the Emperor Napoleon III was captured.…