The First World War did not just happen out of the blue. Although tensions had been mounting across Europe due to territorial disputes and rivalries, many of the continent's superpowers had already sought protection through a complex web of alliances, pacts, and treaties. These agreements stipulated that if one member was attacked, its allies were obligated to mobilize their forces in defense of the threatened nation. As a result, what began as a localized conflict quickly escalated into a full-scale global war.
This article aims to explore the various alliances, pacts, and treaties that compelled the major participants of World War I to enter the conflict. As will become evident, no nation joined the war arbitrarily or without prior connections to either the aggressors or the defenders. Every entry into the battlefield was influenced by existing diplomatic ties, mutual defense agreements, and strategic obligations. They were all answering a call. A call they had pledged to heed when the moment arrived. And now, that moment had come.
Austria-Hungary
Austria-Hungary was the first domino to fall, setting in motion the chain of events that triggered the First World War. Its declaration of war on Serbia stemmed from the assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by a Serbian nationalist. Austria-Hungary issued an ultimatum to Serbia with demands it deemed necessary for justice and peace. While Serbia accepted most of the terms, it repudiated those considered excessive and unjustifiable. This refusal was enough for Austria-Hungary to initiate military action on July 28, 1914.
Serbia
Serbia was drawn into the war automatically and defensively after Austria-Hungary declared war on it. Although Serbia accepted most of the terms in Austria-Hungary’s ultimatum, it rejected one key demand: allowing Austro-Hungarian police and officials to enter Serbia and conduct investigations. Serbia viewed this as a clear violation of its sovereignty.Russia
Russia was drawn into the war by several factors, one of which was its close ethnic and political ties with Slavic states,particularly Serbia. Furthermore, Russia had interests in the Balkan region. Austria-Hungary, backed by Germany, was creating instability in the region, and 'big brother' Russia was compelled to extend a helping hand to Serbia, mobilizing its forces in defense of its ally and to assert its influence in the region.
Germany
Germany entered the war under the obligations of the Dual Alliance, initially signed with Austria-Hungary in 1879 and later updated in 1910. This treaty committed Germany to support Austria-Hungary if it were attacked; particularly by Russia, which had been considered a dominant force in Europe for a long time. When Russia began mobilizing its troops in defense of Serbia, Germany viewed this as an act of aggression against its ally. In response, Germany mobilized its own forces and declared war on Russia on August 1, 1914, fulfilling its obligations.France
Courtesy of the Triple Entente, which was a defensive alliance comprised of Great Britain, France, and Russia, France declared war on the Triple Alliance, which had declared war on Russia. Several treaties set up the formation of the Triple Entente: the Entente Cordiale of 1904 between France and Britain, the Franco-Russian Alliance of 1894, and the Anglo-Russian Entente of 1907. Additionally, France anticipated conflict with Germany due to their longstanding rivalry and unresolved tensions following the Franco-Prussian War of 1870.
Britain
In observance of the Treaty of London (1839), Britain joined the war when Germany attacked neutral Belgium. Britain had vowed to uphold Belgium’s neutrality and attack any country that did not observe the same. Germany invaded Belgium on its way to France as it executed its Schlieffen Plan;a military strategy meant to swiftly take over France. In addition, Britain’s entry was also influenced by its commitments under the Triple Entente, aligning it with France and Russia.Italy
Italy was initially formally aligned with the Triple Alliance during the
outbreak of the war, but public opinion was against its collaboration with her
long-standing arch-enemy Austria-Hungary, and so she switched sides and joined
the Triple Entente powers before formally declaring war on Austria-Hungary. The
Treaty of London (1915), negotiated between Italy and Japan, promised Italy significant
territorial lands in Africa and some parts of Austria-Hungary which were
inhabited by Italian-speaking populations.
Japan
Although Japan had previously dealt with Germany diplomatically and had fought
multiple wars with Russia over territories such as Siberia and Manchuria, its
ambitions in East Asia and the Pacific were a major factor in its decision to
enter World War I. Japan sought to expand its influence over China and seize
Pacific islands under German control.
Its entry into the war was largely influenced by the Anglo-Japanese Alliance of
1902, an agreement with Britain that aimed to protect mutual interests in China
and the Pacific, and to curb Russian expansion in East Asia. When Britain
joined the war against Germany, Japan honored the alliance by first offering an
ultimatum to Germany, then subsequently declaring war on Germany on August 23,
1914, marking its formal entry into the conflict.
