Although there were many underlying reasons for the European nations to break out in war, the early days of the fighting between Serbia and Austria caused the expansion of the war, along with the alliances which failed to remain peace and actually contributed to the war. Also, the possibility of remaining neutral and prepared is always another alternative, rather than forming allies that may require the nation to enter a war. A war between Serbia and Austria caused 7 nations to enter the fighting, justified by the reason of supporting alliances previously formed and underlying conflicts.
Initially, World War I was spurred by the assassination of Arch Duke Ferdinand of Austria on June 28th of 1914 by a terrorist recruited by Serbia. When Austria seized the provinces of Bosnia and Herzegovina in 1908, Russia and the independent state of Serbia became infuriated and retaliated with the murder of Ferdinand and his wife.
On July 23rd the Austrian Government declared war against Serbia. Germany declared war against Russia, an ally of Serbia, on August 1st, then declares war on France, an ally of Russia, and begins invading through neutral Berlin. On August 4th Great Britain, declared war against Germany due to their brutality of the invasion of neutral Berlin, along with remain true to their alliance with France.
Secret alliances that were formed by many of the European nations, which bounded them to one another, failed to maintain the peace and thus contributed to the war. In 1879 Germany had entered into a defensive alliance with Austria-Hungary, known as the 'Dual Alliance' against Russia and France. Then, in 1882, Italy joined the Dual alliance, forming the Triple Alliance. Italy negotiated with France, forming a secret treaty that decided Italy would remain neutral if Germany attacked France. Russia entered into a...