Britain, led by Prime Minister Herbert Asquith, had given Germany an ultimatum to remove their troops from Belgium by midnight of August 3rd.
Germany's invasion of Belgium occured as part of their plan to knock France out of the war quickly, before switching to attack Russia. This plan, known as the schlieffen plan, had challenged the 1839 treaty signed by the UK, that guaranteed Belgian soverignty.
Seen by the German's as 'just a piece of paper' this treaty left Asquith with a very simple decision to make – but one that would have a cataclysmic impact on British society. He could either turn a blind eye to a war in mainland Europe that might have little impact on Britain if she stood as a neutral. Or the British public could see Asquith as the man who stood up to the perceived bullying of Germany and who stood for righteousness and decency. A future Prime Minister, Winston Churchill, described the scene in London in the hours that led to the declaration of war.
“It was eleven o’clock at night – twelve by German time – when the ultimatum expired. The windows of the Admiralty were thrown wide open in the warm night air. Under the roof from which Nelson had received his orders were gathered a small group of admirals and captains and a cluster of clerks, pencils in hand, waiting. Along the Mall from the direction of the Palace the sound of an immense concourse singing ‘God save the King’ flouted in. On this deep wave there broke the chimes of Big Ben; and, as the first stroke of the hour boomed out, a rustle of movement swept across the room. The war telegram, which meant, “Commence hostilities against Germany”, was flashed to the ships and establishments under the White Ensign all over the world. I walked across the Horse Guards Parade to the Cabinet room and reported to the Prime Minister and the Ministers who were assembled there that the deed was done.”
In Britain, Asquith addressed a packed House of Commons saying:
“We have made a request to the German Government that we shall have a satisfactory assurance as to the Belgium neutrality before midnight tonight. The German reply to our request was unsatisfactory.”
Asquith explained that he had received a telegram from the German Ambassador in London who, in turn, had received one from the German Foreign Secretary. Officials in Berlin wanted the point pressed home that German forces went through Belgium to avoid the French doing so in an attack on Germany. Berlin had “absolutely unimpeachable information” that the French planned to attack the German Army via Belgium.
Asquith stated that the government could not “regard this in any sense a satisfactory communication.”
“We have, in reply to it (the telegram), repeated the request we made last week to the German Government that they should give us the same assurance with regard to Belgium neutrality as was given to us and to Belgium by France last week. We have asked that a reply to that request and a satisfactory answer to the telegram of this morning, should be given before midnight.”
Nothing of the sort was received and the Foreign Office released this statement:
“Owing to the summary rejection by the German Government of the request made by His Majesty’s Government for assurances that the neutrality of Belgium would be respected, His Majesty’s Ambassador in Berlin has received his passport, and His Majesty’s Government has declared to the German Government that a state of war exists between Great Britain and Germany as from 11pm on August 4th.”