The declaration of war against Serbia did not leave other European States indifferent to the situation. In the last years of the 19th century a number of alliances were formed between several states which undertook to defend an Ally in case of an attack. There were the Triple Agreement (formed between the Russian Empire, France and Great Britain) and the Triple Alliance (the Austro-Hungarian Empire, Germany and the Kingdom of Italy).
These agreements were followed by others treaties that were considered of minor importance in the context of the chessboard of European powers. One of them was a treaty between Serbia and Russia which, after the ultimatum by Austria-Hungary, was the first one to be invoked. Czar Nicholas II respected the pact and on 31st July mobilized his troops in aid of Serbia, convinced like many other statesmen and military commanders of the time that this latest war would soon come to an end and would remain confined to the Balkans.
This decision sparked off a reaction by neighbouring Germany which on the next day (01st August 1914) in turn declared war against Russia. Neither did France remain impassive and respecting the terms of the Triple Agreement, joined forces with its Russian ally and in this way came under a declaration of war by Germany (03rd August). The decision by Germany to attack France by way of the invasion of Belgium (which had declared itself neutral) also led to the involvement of Great Britain which went to war against Berlin. Two days later it was the turn of Austria-Hungary that first officially declared that it was at war with Russia and then, on 11th and 12th August, received a declaration of war by France and Britain.
Without even realizing, in the space of two weeks Europe found itself involved in a tremendous war. Compared to the past, the speed of communications (thanks to the recent inventions of telegrams, telephone and printed communications) triggered this rapid chain reaction. Many statesmen and diplomats were unable to control their feelings and rash reactions prevailed over considered opinions. Armies started moving rapidly: the Great War had begun.
