What systems and events led to the outbreak of the first world war in Europe

The outbreak of the First World War in 1914 was due to a combination of causes which were both long-term and short-term: alliances, militarism, imperialism, nationalism, and the assassination of Archduke Franz Ferdinand ... The alliance system caused tension in Europe for several reasons.

WWI occurred for a lot of reasons. One of the reasons was that during that period European Countries believed that the only way to economic growth and to gain respect from other countries was through Imperialism, which meant that they believed that the only way was through war and expansion of territories, nationalism, and militarism. This led to a series of secret alliances between countries which eventually led to war because of the break of other secret alliances. Once Archduke Franz Ferdinand was assassinated, it led to a domino effect, Russia started to mobilize to defend its alliance with Serbia, Germany declared war on Russia and the war expanded.