Colored images of the First World War show soldiers on the western front and in the Somme trenches

Archduke Franz Ferdinand, pictured, was killed in Sarajevo, the capital of Bosnia and Herzegovina, along with his Serbian wife, Sophie, on June 28, 1914.

Archduke Franz Ferdinand, pictured, was killed in Sarajevo, the capital of Bosnia and Herzegovina, along with his Serbian wife, Sophie, on June 28, 1914.

Archduke Franz Ferdinand, pictured, was killed in Sarajevo, the capital of Bosnia and Herzegovina, along with his Serbian wife, Sophie, on June 28, 1914.

In the event, which is widely accepted as the beginning of the First World War, Archduke Franz Ferdinand, nephew of Emperor Franz Josef and heir to the Austro-Hungarian Empire, was shot dead.

He was assassinated in Sarajevo, the capital of Bosnia and Herzegovina, together with his Serbian wife, Sophie, on June 28, 1914.

Finally killed by Gavrilo Princip, 19, the couple had been attacked that same day by another man who threw a grenade at his car.

Archduke Ferdinand was shot in the neck, while his wife was hit in the abdomen. It is believed that the assassination began a domino effect that led to the break-up of World War I a month later.

Princip and others wanted Bosnia to become part of Serbia. Austria-Hungary, like many in countries around the world, blamed the Serbian government for the attack and hoped to use the incident as justification to solve once and for all the question of Slavic nationalism.

While Russia supported Serbia, an Austro-Hungarian declaration of war was delayed until its leaders received assurances from German leader Kaiser Wilhelm that Germany would support its cause in the event of a Russian intervention, which would likely involve Russia's ally, France and possibly Britain. as well.

On July 28, Austria-Hungary declared war on Serbia, and the tenuous peace between the great European powers collapsed. In a week, Russia, Belgium, France, Great Britain and Serbia had aligned themselves against Austria-Hungary and Germany, and the First World War had begun.

The artillery units of Austria-Hungary began to rain projectiles on Belgrade, the Serbian capital, the first planes of the First World War.

That attack was to begin a chain reaction that, in a matter of weeks, involved all the great world powers in a global war that mobilized more than 70 million soldiers. The Great War, as it would soon be known, was the first military conflict that was waged on an industrial scale.

But the technological advances that led to increases in the lethality of weapons were not matched by changes in strategy, with both sides resorting to virtually suicidal human wave attacks.

Although much of the war took place in Europe, the battle soon joined the entire planet through the colonies of European imperial powers.

In 1918, the powers of Central Europe were exhausted by struggle. A last-minute final offensive along the Western Front by Germany was successfully repulsed and, when US forces began to enter the trenches, the Allies made a series of successful advances, forcing the enemy to surrender on November 11.

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