The assassination of Franz Ferdinand on the 28th June, 1914, precipitated WW1. He was shot by Gavrilo Princip, a member of the Black Hand, a Serbian group set up to fight for the unification of all South Slav territories that had been annexed by Austria-Hungary. Two months after the shooting Austria-Hungary declared war on Serbia, setting off the next chain of events that brought into account the alliance system. In 1938, a year before the start of WW2, Hitler was growing ever more confident due to the lack of resistance he experienced from any other European countries. He had annexed Austria with little or no consequences, and made a deal with France and Britain guaranteeing him the Sudetenland if he did not go after any other territories. In 1939 he broke this deal by occupying Czechoslovakia, and starting to advance on Danzig. This caused France and Britain to panic, and gather allies about themselves.
The alliance system was present throughout both wars, although as countries surrendered and changed loyalties none of them remained permanent. The alliances system was originally created to help keep the peace in Europe, with the belief that they would be as if communities, with it in their own interest to prevent any wars. The alliance system is now seen as a major cause of the war, as two small countries with a territorial dispute were able to set of a chain in the alliances that brought the greatest powers in Europe to declare war on each other.
The Wall St. Crash of 1929 is believed to have led to the Great Depression of the 1930s, and caused there to be 6 million unemployed in Germany. This