Why did World War I begin? As with most wars the reasons behind why the Great War began seem like a difficult task to untangle, but in reality, they are fairly easy to distill. The following, in no particular order, are the 4 main reasons for the war to break out in the autumn of 1914:

1. Why did World War I begin? Nationalism–this is the belief that your country is #1, and all others are inferior to yours.

2. Why did World War I begin? Alliances—these are agreements among nations that guarantee that if your ally is attacked, your country will join the fight against the aggressor. There were 2 main alliances:

                        A. Triple Entente—France, Russia, Great Britain.

Versus             B. Triple Alliance—Germany, Austria-Hungary, Italy.

3. Why did World War I begin? Imperialism/Colonialism—is the basic take-over of one country by another country, and usually includes economic exploitation and forcing the weaker country to accept the customs and beliefs of the superior power.

As the map above shows, much of the world was controlled by European powers by 1914.  This led to jealousy between these European powers to see who could grab control of a new region, mainly to exploit that country’s wealth.

4. Why did World War I begin? Militarism—the belief that the military should have a strong profile in a society, sometimes promoting itself over the common civilian population.

Another reason why World War I began was the “arms race.” Mainly a race between Great Britain and Germany for the high seas, it became a race to see who could build a bigger, more powerful battleship. When the HMS Dreadnought was launched by Great Britain in 1906 it made all other battleships obsolete. With its ten 12-inch guns and a speed of 24 miles per hour, Germany was forced to compete even at even a faster rate than before.

Above, the HMS Dreadnought, 1906.

With all of these tensions rising in Europe it was only a matter of time before things would explode. The “spark” that set WWI in motion occurred on June 28, 1914 when Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, and his wife Sophie were murdered in broad daylight in Sarajevo.


On that fateful day, a secret organization made up of mostly Serbians called the Black Hand, executed a plan to kill the visiting royal couple in Sarajevo, Bosnia-Herzegovina. This group, among others, wanted a greater Serbia and chafed under the Austro-Hungarian Empire. The Serbians also wanted the Austro-Hungarian empire to release its ever-increasing control over Bosnia Herzegovina.

At 10:45am, as the royal motorcade was proceeding along the river in downtown Sarajevo, the driver made a wrong turn, and at that moment 19-year-old Gavrilo Princip gunned down both the Archduke and his wife as they sat in their car. Both victims would be dead by 11:30am.

The Austro-Hungarian Empire believed that the Serbian government was behind the murder of its heir apparent, and demanded that they be a part of the investigation and prosecution of the perpetrators. They gave Serbia a 48-hour ultimatum.

Serbia believed the Austro-Hungarians were preparing to attack, and asked Russia (fellow Slavs) to come to their aid if and when the attack occurred.

This is when the system of alliances came into play and so began the unstoppable march to war. Germany had secretly backed the Austro-Hungarian attack on Serbia via their alliance. On July 28th Austro-Hungary declared war on Serbia. On the other side, when Russia joined in, that brought in its fellow alliance member France and the snowball effect was in full swing!

By the beginning of August, 1914, Austria-Hungary and Germany were at war with Russia, France, Great Britain and Serbia: the greatest war in the history of humankind had begun.

The first attack of the war began on August 4th, when Germany put into use the “Schlieffen Plan,” developed by German Field Marshall Alfred von Schlieffen in 1905. This master plan involved the main Germany army attacking France NOT through their common border, but via neutral Belgium, in an arcing maneuver (see map on left). The German goal was to quickly out-flank the French Army and take Paris, France

Too, when Germany violated Belgium’s neutrality, England sent 100,000 soldiers across the English Channel to help defend Belgium from the invaders.

As each country joined World War I this conflagration spread around the globe to their colonies and possessions overseas, making it the first truly global war: The Great War had begun.

Sadly, both sides of the conflict believed that the war would be over by Christmas, 1914.