Escalation of Events

The July Crisis

The assassination of archduke Franz Ferdinand.
There had been numerous crises in Balkan region and it was generally seen as a chaotic and dangerous place.
It was very unstable as it had been under the rule of the Ottoman Empire.
Many countries fought for independence.
The first country that got its independence was Greece.
An example is the Russo-Turkish war from 1877 to 1878, where Russia wanted to help the nations fighting for independence, while also maybe gaining some important territory.
Russia won with some difficulty.
Austria wanted to expand into the Balkans (due to imperialism).
It was an interest of the great powers due to the many strategic positions (as it was next to the Mediterranean sea).
Austrian archduke Franz Ferdinand visited Sarajevo on June 28th 1914 to oversee military maneuvers.
He and his wife were assassinated by Gavrilo Princip, a member of the Serbian Black Hand terrorist organization.
The problem was that the Serbian Black Hand was a nationalist military organization, some members of which were part of the Serian military.
This indirectly tied the organization to the Serbian government.
This led to a crisis between Serbia and Austria-Hungary.
Ultimatum from Austria-Hungary to Serbia.
Austria-Hungary needed support and sought out Germany, as if they attempted to do anything themselves they would likely result in a crisis with Great Britain and Russia.
Germany agreed to support Austria Hungary with whatever they decided to do.
Serbia was backed by Russia.

Serbia didn't comply to the ultimatum which led to the Third Balkan War.
Austria-Hungry fought Serbia.
It would probably have been localized in the Balkans and been a rather small war.
However it escalated into the Great War.
There were conversations between the great powers of Europe as they were uncertain if nations backed each other up it could lead to a war.
One of Germany's fears was that they would have to fight a two-front war against France and Russia.
They decided that if there was a danger of war, Germany had to act quickly.
They planned to attack France first and take them out first.
Then they could focus on Russia.
However the situation was uncertain so they wanted to both avoid the war but also wanted to be the first to attack in a war.
Eventually Germany decided to attack with the start of the Third Balkan War.
The miscommunication and attack and countries backing eachother up lead to the Great War.

Germany attacks France on the 4th of August in 1914.
Austria Hungary declares war on Serbia on July, 1914.
Russia declares war on Austria-Hungary.
Germany declares war on Russia.
Germany declares war on France.
Great Britain declares war on Germany.
Austria-Hungary declares war on France.
France and Great Britain declare war on Austria-Hungary.
Ottoman Empire and Bulgaria support Germany.
Italy joins the Allied side in 1915
Italy didn't join the Central Powers as they were in a defensive pact and weren't obligated to support Germany as they were the aggressors.

When the war broke out, there was succession of declaration of war.
Everyone declared war on each other, leading to the war being spread around Europe, and later to colonies.
Allies were essential in war. This was due to the fact that allies, even if not successful, were very important as they busied enemy troops, preventing full on attacks.

Nations had militarized greatly.
Imperialism.
Nationalism and rivalries.
Social/cultural Darwinism, meaning that nations wanted to fight others to protect their cultures.
Old grudges such as between France and Germany (Franco-Prussian war from 1870-1871).
The kings of most European nations were related, thus it could be familial grudges.
High tensions between countries and suspicions, which led to miscommunication.
The assassination of the archduke Franz Ferdinand was the bursting point for all the pent-up tension.