One Thing Led to Another

So then, we have the following remarkable sequence of events that led inexorably to the 'Great War' - a name that had been touted even before the coming of the conflict।

1. Austria-Hungary, unsatisfied with Serbia's response to her ultimatum (which in the event was almost entirely placatory: however her jibbing over a couple of minor clauses गावे
2. Austria-Hungary her sought-after cue) declared war on Serbia on 28 July 1914।
3. Russia, bound by treaty to Serbia, announced mobilisation of its vast army in her defence, a slow process that would take around six weeks to complete।
4. Germany, allied to Austria-Hungary by treaty, viewed the Russian mobilisation as an act of war against Austria-Hungary, and after scant warning declared war on Russia on 1 August।
5. France, bound by treaty to Russia, found itself at war against Germany and, by extension, on Austria-Hungary following a German declaration on 3 August. Germany was swift in invading neutral Belgium so as to reach Paris by the shortest possible route।
6. Britain, allied to France by a more loosely worded treaty which placed a "moral obligation" upon her to defend France, declared war against Germany on 4 August. Her reason for entering the conflict lay in another direction: she was obligated to defend neutral Belgium by the terms of a 75-year old With Germany's invasion of Belgium on 4 August, and the Belgian King's appeal to Britain for assistance, Britain committed herself to Belgium'sdefence later that day। Like France, she was by extension also at war with Austria-Hungary.
7. With Britain's entry into the war, her colonies and dominions abroad variously offered military and financial assistance, and included Australia, Canada, India, New Zealand and the Union of South Africa।
8. United States President Woodrow Wilson declared a U.S. policy of absolute neutrality, an official stance that would last until 1917 when Germany's policy of unrestricted submarine warfare - which seriously threatened America's commercial shipping (which was in any event almost entirely directed towards the Allies led by Britain and France) - forced the U.S. to finally enter the war on 6 April 1917
9. Japan, honouring a military agreement with Britain, declared war on Germany on 23 August 1914। Two days later Austria-Hungary responded by declaring war on Japan.
10. Italy, although allied to both Germany and Austria-Hungary, was able to avoid entering the fray by citing a clause enabling it to evade its obligations to both. In short, Italy was committed to defend Germany and Austria-Hungary only in the event of a 'defensive' war; arguing that their actions were 'offensive' she declared instead a policy of neutrality. The following year, in May 1915, she finally joined the conflict by siding with the Allies against her two former allies.
    The Tangle of Alliances

Such were the mechanics that brought the world's major nations into the war at one time or another। It's clear from the summary above that the alliance system was as much at fault as anything in bringing about the scale of the conflict.

What was intended as a strictly limited war - a brief war - between accuser and accused, Austria-Hungary and Serbia, rapidly escalated into something that was beyond the expectations of even the most warlike ministers in Berlin (and certainly Vienna, which quickly became alarmed at spiralling events in late July and sought German reassurances).
It's possible to delve deeply into European history in the quest to unearth the roots of the various alliances that were at play in 1914. However, for our purposes it serves to date the origins of the core alliances back to Bismarck's renowned intrigues, as he set about creating a unified Germany from the loose assembly of German confederated states in the 1860s