What two things played a role in causing ww1, and explain each

Archduke Franz Ferdinand-Assassinated by a Serbian terrorist group called the Black Hand. This was the IMMEDIATE cause of World War 1.

The war started mainly because of four aspects: Militarism, Alliances, Imperialism and Nationalism. This is because big armies become potential threats to other countries, other countries started forcing alliances in order to secure land. Imperialism was a cause because building an empire needs manpower such as an army and a navy to conquer and keep the land that they colonised. The alliances system meant that a local conflict could easily result into an intimidating global one. The overall cause of World War was the assassination of Archduke Franz Ferdinand.

https://medium.com/@dhireshnathwani/what-was-the-most-significant-cause-of-world-war-one-ww1-74bb9e815e37

john maynard keynes developed new economic theories in response to the stock market crash of 1929. great depression of the 1930s. first and second world wars. economic boom of the 1950s.