Key Events and Phases of World War I

What Was the Arms Race?

The Arms Race was a competition between nations for armament superiority. Countries spent their resources strengthening their armies, preparing for a war that could start at any moment.

Why Was Italy on Both Sides?

Italy was initially part of the Triple Alliance with Germany and Austria-Hungary, but in 1915, it switched sides and joined the Allied Powers (Britain, France, and Russia) in exchange for territorial promises. The Italian government believed that siding with the Allies would result in territorial gains in the Balkans and the Adriatic Sea, which they had long sought. While Italy was with Germany and Austria-Hungary, they signed a secret agreement with France. Italy finally joined the Triple Entente with France and Great Britain.

The Outbreak of the War

On June 28, 1914, Franz Ferdinand, heir to the Austro-Hungarian Empire, was assassinated in Sarajevo (Bosnia) by Gavrilo Princip, a Serbian nationalist member of the “Black Hand,” a terrorist group. Following this:

• Austria-Hungary declared war on Serbia.
• Russia declared war on Austria-Hungary to protect Serbia.
• Germany declared war on France.
• Italy initially remained neutral.

Phases of the First World War

War of Movement (1914–1915)

This phase started with the German invasion of Belgium and France in August 1914. Initially, both sides thought the war would be short and fought in the open with rapid movements. However, the conflict became more complex and costly as both sides fortified positions. The war of movement ended in 1915 with the Battle of the Marne and the failure of the German Schlieffen Plan.

Trench Warfare (1915–1917)

This phase was characterized by the establishment of trenches and the use of modern weapons such as machine guns, artillery, and gas. The front lines barely moved, and millions of soldiers spent years in squalid, deadly conditions. Major battles included:

• Battle of Verdun
• Battle of the Somme

New technologies such as tanks, flamethrowers, and airplanes were developed, though they did not immediately change the nature of the war. This phase ended with the Battle of Cambrai in 1917, which marked the first successful large-scale use of tanks.

Last Phases of the War (1917–1918)

During this phase, the Allies gained the upper hand and pushed back the Central Powers. The entry of the United States into the war in 1917 was a significant factor. The war became more mobile again as the use of tanks and aircraft increased. Key engagements included the Battle of Amiens and the Meuse-Argonne Offensive. The war ended with the Armistice of November 11, 1918.