At the outbreak of hostilities in 1914, the British were an unknown quantity. Their Liberal government was horrified at the prospect of war. The Germans were counting on that queasiness to overrule the British commitment to uphold Belgian neutrality as promised under the London Treaty of 1839. The German invasion of France, as dictated by The Schlieffen Plan, depended on the armies being able to swing south through Belgium. On August 2, 1914, Germany demanded right of passage for their troops to march through Belgium. The Belgians refused. The Germans came anyway and Belgium found itself at war.
The British responded by delivering an ultimatum. Germany ignored it. They had delivered their own ultimatum to Belgium, in which they promised to leave their territory upon cessation of hostilities and to make reparations for any damage caused by the troops. No one believed that for a minute. Belgian Premier Charles de Broqueville said, “If Germany is victorious, Belgium, whatever her attitude, will be annexed to the German Empire.”
German troops entered Belgium on August 3, 1914 and Britain declared war on August 4th. Britain would enter a war in which she had not been directly affronted. German Field Marshall Helmuth von Moltke knew the British would enter the war with or without Belgian violation. He said, “[England] … fears German hegemony and true to her policy of maintaining a balance of power will do all she can to check the increase of German power.”
The B.E.F. – British Expeditionary Force had first been organized in 1907. Behind the scenes, an inner circle of the British government had made greater commitments to France in case of war than was widely known to the public. Nevertheless, the commitment to the cause was to be rather small: four infantry divisions plus cavalry and artillery; no more than 100,000 men. Compared to the 2 million invading Germans, this was a drop in the bucket. However, in the beginning, British involvement was as important for what it symbolized -allegiance with France- as for what it actually contributed. When asked the minimum number of British troops with which France would be content, the politician Georges Clemenceau famously replied, “One, and we shall take good care to get him killed.” The British plan largely consisted of falling in on the French left flank and following their lead.
By the time the B.E.F. reached position in Mauberge on August 20, the fighting was well under way. France’s offensive in Lorraine was in trouble and Belgium was being destroyed.