Russia ordered its forces to prepare for war on 30 July. While the Russians viewed this mobilisation as a precaution in case war broke out, the Germans saw it as an aggressive act of war directed against itself and Austria-Hungary. Germany’s war plan was time-sensitive, being based upon beating France before Russia could get its army fully into action.
On 31 July, Germany sent an ultimatum to Russia demanding it demobilise. The next day, this ultimatum expired without a reply. Germany declared war on Russia and ordered its own general mobilisation. France knew that it faced German invasion, but was clear that it must stand or fall with Russia.
From 24 July, British Foreign Secretary Sir Edward Grey tried to organise an international peace conference to prevent further escalation. Although France accepted his proposals, Germany refused.
After declaring war on France, Germany was now determined to execute its war plan to defeat France first and then concentrate its forces against Russia. The plan required German troops invade Belgium to get to France. This would be in direct violation of Belgium’s neutrality, which had been guaranteed in a treaty signed by major European powers, including Britain, in 1839. On the evening of 2 August 1914, Germany demanded that its troops be allowed to pass through Belgian territory. Belgium refused. Accepting Germany’s demands would make Belgium complicit in the attack on France and partially responsible for the violation of its own neutrality.
Germany’s invasion of Belgium tipped the balance for Britain. At 2pm on 4 August, it issued an ultimatum demanding Germany withdraw its troops. At 11pm, the deadline passed without a reply. Britain declared war. Britain’s entry into war was partially a reaction to larger anxieties about the balance of power in Europe, as well as its own security and position in the world. But by violating Belgium’s neutrality, Germany positioned itself as the belligerent aggressor and made British intervention a moral issue about the rights of small nations.
Sure, all nations have a share of the blame, but as even Christopher Clark (the author of Sleepwalkers) said (Graham’s College speech):
For that matter to those studies that blame Russia or France for the outbreak of War, which I think is, equally um an equally, equally, serious misprision of how this war came about…
This war was the fruit of - was the consequence of decisions made in many places with whose effect, of course, was cumulative and interactive; with decisions made by a gallery of actors who shared a fundamentally similar political culture.It was genuinely complex not just complicated but complex. It was genuinely multi-polar and it was genuinely European and it was to highlight or to illuminate these aspects of the story of how this world, this war, came into the world that I wrote this book and I thank you.