The spark which set Europe (and the rest of the world) alight was the assassination of the Austrian Archduke Franz Ferdinand by a Serb nationalist on 28th June, 1914.
Austria blamed Serbia, which then looked to Russia for support. Germany declared war on Russia in support of Austria and on France because of her alliance with Russia.
Britain declared war on Germany in support of Belgium and France, and on Turkey because of her alliance with Germany.
Britain declared war on Germany on August 4th 1914, but rivalry between the two countries had been growing for years. Germany resented Britain’s control of the world’s oceans and markets, while Britain increasingly viewed a Europe dominated by a powerful and aggressive Germany as a threat which must be contained.
Europe was now divided into the Central Powers (Germany, Austria-Hungary, Turkey and their allies) and the Triple Entente (Britain and the British Empire, France and Russia and their allies), with countries such as Spain, Albania, Norway, the Netherlands and Sweden remaining neutral.
Soon however most of the major nations of the world would become involved in the war. Australia, Canada, India and New Zealand became involved as part of the British Empire. In much the same way, colonies of the other European nations also entered the war, including many Asian and African countries. Initially neutral, the United States of America entered the war on April 6th 1917.
The Path to War:
1. The assassination of the Austrian Archduke Franz Ferdinand by Serb nationalist – 28th June 1914
2. Austria-Hungary declares war on Serbia – 28th July 1914
3. Germany declares war on Russia – 1st August 1914
4. Germany invades Belgium – 3rd August 1914
5. Germany declares war on France – 3rd August 1914
6. Britain declares war on Germany – 4th August 1914
7. Austria-Hungary declares war on Russia – 6th August 1914
8. Britain declares war on Austria-Hungary – 12th August 1914
9. Russia declares war on Ottoman Turkey – 2nd November 1914
10. Britain declares war on Ottoman Turkey – 5th November 1914
11. Italy declares war on Austria-Hungary – 23rd May 1915
12. Bulgaria declares war on Serbia – 14th October 1915
13. Britain declares war on Bulgaria – 15th October 1915
14. Russia declares war on Bulgaria – 19th October 1915