On June 28, 1914, Archduke Franz Ferdinand of Austria, the heir to the Austro-Hungarian throne, was assassinated by a Serbian nationalist in Sarajevo, the provincial capital of Bosnia-Herzegovina (formally annexed by Austria-Hungary in 1908). Britain had no direct connection to this event but its consequences would profoundly impact the nation.
Alliances and Entanglements:
Austria-Hungary issued an ultimatum to Serbia, which was seen as provocative and unreasonable by many European powers, including Russia, the patron and protector of Serbia within the complex web of alliances that characterized pre-war Europe. Russia began mobilizing its forces, and Germany, allied with Austria-Hungary, responded by declaring war on Russia on August 1, 1914, followed by France, Russia's ally.
The Schlieffen Plan:
Germany's military strategy, the Schlieffen Plan, relied on quickly defeating France before turning to face Russia. This required violating the neutrality of Belgium, which Britain had guaranteed under the 1839 Treaty of London. By August 4, 1914, German troops had entered Belgium, prompting Britain to declare war on Germany.
Public and Political Sentiment:
Public sentiment in Britain was strongly in favor of defending Belgium and honoring the nation's treaty obligations. The violation of Belgian neutrality was seen as a breach of international law and a threat to British interests and security. Political leaders across the spectrum supported involvement, with Prime Minister Herbert Asquith declaring that "Britain could not stand aside while friendly nations are being trampled upon."
Economic Considerations:
Britain had significant economic ties with both France and Russia and the disruption of trade and commerce due to the war posed a threat to the nation's economy. British financial interests were also at stake, as loans and investments in both Russia and France could be jeopardized by their defeat.
Maintaining the Balance of Power:
Britain had a long-standing policy of maintaining a balance of power in Europe to prevent any single power from becoming dominant and threatening British interests. The rise of Germany as a powerful industrial and military force challenged this balance, and Britain's entry into the war was seen as necessary to counter German expansionism and preserve the existing European order.
In summary, Britain's involvement in World War I was primarily driven by the violation of Belgian neutrality, a sense of obligation to its allies, public sentiment, economic considerations, and the need to maintain the balance of power in Europe.