Germany’s plan to quickly win the war in the West, before turning her full attention to the Eastern Front, known as the Schlieffen Plan, essentially involved a speedy attack through neutral Belgium and into Northern France. It was then anticipated that the German army would encircle Paris and turn back on itself, trapping the French army on the border between France and Germany. The final straw, however, came with the German invasion of Belgium – a country whose neutrality Great Britain had sworn to protect. Therefore, on 4th August 1914, Great Britain declared war on Germany.
Right until the last minute, the Germans had doubted that Britain really would defend Belgium, but in this instance it was not just a matter of British pride, but also a desire to teach the Germans a lesson. The general populations of each country firmly believed that they had right (and in most cases, God) on their side, so civilian support was strong. Most agitators abandoned, or suspended their campaigns until the end of the conflict, so while war was breaking out all over Europe, internally, many countries were more at peace than they had been for years.