Numerous factors have been attributed to the causes of World War I, ranging from nationalism to colonial rivalry. Of course, the immediate events that precipitated the war can be traced. However, it is crucial to acknowledge that, in many ways, World War I was an accidental conflict. It was a war that none of the combatants genuinely desired. The leaders of the opposing Alliances were often friendly, even blood relatives. They commanded competing nations, yet many European countries believed that war was unthinkable at the time. Trade between European countries had reached a staggering 30% of the average European Gross National Product by 1914. The widely held theory, which was subsequently proven erroneous, asserted that countries engaged in trade would not engage in conflict. Therefore, why did war occur despite this apparent consensus?

Nationalism was on the rise in European countries, manifesting both within the larger powers, such as Germany, and in smaller states like Bosnia, which yearned for independence. This nationalism led to increased competition for the remaining colonies and heightened military spending. Notably, naval spending was particularly evident, with Germany embarking on the construction of massive battleships to challenge the British navy. Naval dominance was a significant source of British power, particularly considering its limited standing army.

The primary cause of World War I, however, was the series of alliances that had been established among European countries. These alliances were defensive in nature, obligating the nations to provide mutual support in the event of an attack. This situation was further exacerbated by the military strategies employed by various countries, which compelled them to take offensive actions. The most prominent of these strategies was the Sheffleian Plan, which guided the German military. This plan envisioned the German army attacking France, which was allied with Russia in the event of a conflict with Russia.

In the preceding years leading up to the outbreak of World War I, several crises had arisen between the European powers. The first was the First Moroccan Crisis in 1905, where Germany attempted to expand its influence in Morocco but was unsuccessful. In 1908, a crisis was created when Austria-Hungary annexed Bosnia, which had been part of the Ottoman Empire. Although Russia objected, they eventually acquiesced. The second Moroccan Crisis occurred in 1911 when Germany dispatched a warship to Morocco, leading to a German retreat. These events heightened tensions in Europe and diminished the likelihood of compromise during future crises.

The immediate sequence of events leading to the outbreak of the war was as follows:

June 28, 1914: Archduke Franz Ferdinand, the heir to the Austrian throne, was assassinated by a Serb nationalist while visiting Sarajevo.
July 5, 1914: Germany provided Austria-Hungary with its tacit approval for any actions they desired against Serbia.
July 23, 1914: Austria-Hungary issued an ultimatum to Serbia, demanding that it accept all but one of its demands. Serbia accepted all but one point.
July 28, 1914: Austria-Hungary rejected Serbia’s response and declared war.
July 29, 1914: Austria-Hungary commenced shelling Belgrade.
July 30, 1914: Russia initiated its mobilization.
July 31, 1914: Germany demanded that Russia cancel its mobilization.
August 1, 1914: Germany declared war on Russia, and France mobilized.
August 2, 1914: Germany demanded the right to send troops across Belgium, which Belgium refused.
August 3, 1914: Germany declared war on France and sent troops into Belgium.
August 4, 1914: Britain declared war on Germany.