What caused the First World War to break out in 1914?

The First World War broke out as a result of several long term causes and one short term trigger. It is impossible to explain the war with just one cause, because it was caused by a variety of interlinking factors. The long term factors stretch as far back as the 19th century and include imperialism, militarism and nationalism. This very much involved a struggled between European powers to expand their empires and gain new colonies. The war was precipitated by the short term trigger which was the assassination of Archduke Franz Ferdinand on 28 June 1914. This essay will explore these factors, and conclude that it was no single factor which caused World War One to break out, but instead a unique combination of events.