On 28 June 1914, the heir to the Austrian throne, Archduke Franz Ferdinand, was shot by a Serbian nationalist while visiting the city of Sarajevo. With the backing of its ally, Germany, Austria presented an ultimatum to Serbia. The Austrians demanded that the Serbs rein in the nationalist and anti-Austrian movements hatching plots in their territory. When the Serbs responded with a reply the Austrians deemed unsatisfactory, Austria declared war.

While Germany was allied with Austria, Russia was allied with Serbia. The Russians feared that they would be at a disadvantage if war broke out and Germany had completed its military preparations before them. The Russian tsar thus ordered a general mobilization. Germany also mobilized and, to avoid fighting Russia and France at the same time, decided to launch a knockout blow against France by striking west through Belgium. Because Britain was committed by treaty to Belgian independence, it declared war on Germany. World War I had started.

When we think of World War I, we generally think of trench warfare on the western front in France. It is important to understand, however, that World War I was truly a world war. As a matter of fact, although the British and French referred to the war as the “Great War” until World War II, the Germans coined the phrase “world war” early on to describe the conflict. German strategists understood that the war was being waged among rival empires with worldwide interests. These empires depended on their colonial possessions to maintain their strategic position and economic well-being. Colonies were also indispensable for the French and British military effort, since both powers depended on them for manpower to replenish the depleted ranks of their armies.