In the early 1900's the world was becoming much more interconnected. The first successful telegraph line from the US to Europe was completed in Trade increased among the US, Europe, and the rest of the world. Imperialism brought the countries into contact with each other, and led to competition for trade, and conflict.

One of the main causes of World War I was Nationalism Nationalism is defined as the desire of people with similar cultures to have their own independent countries. It is identified by intense devotion to one's culture or nation. Do not confuse nationalism with patriotism.

Often, nationalism led to rivalries and bad feelings among nations. In this atmosphere of competition, many Europeans feared Germany's growing power. Examples of nationalism: Germany took two territories from France in the 1871 Franco-Prussian War: Alsace and Lorraine. France was angry about what they called the theft of their land, and wanted those areas back. Why? Because a lot of the people in Alsace and Lorraine spoke French.

The most important example of nationalism, though, was Bosnia. This tiny area was owned by Austria-Hungary, but shared a language and religion with Serbia. Serbia hated the fact that Bosnia was owned by Austria-Hungary, and sought to make Bosnia part of Serbia. Russia considered Serbia its "daughter nation." Russia shares a language and religion with Serbia, and tends to watch out for its welfare.

Another cause of World War I was Militarism Militarism means the development of armed forces and using them as a tool of diplomacy. Historically, nations did not keep large armies during peace time. (They're too expensive) Just before World War I, European nations started building large armies and navies. Why?

Imperialism had a lot to do with that, too. If you're going to start colonies all over the world, you need a navy to get to them, and an army to protect them. Plus, if your neighbor builds up his army and you don’t, you're open to attack and unable to defend yourself. So, you have to build up your army too. This leads to a situation where the nations of Europe had huge armies, and they were all suspicious of each other; they were prepared and waiting for war, anticipating some event to touch it off.

Yet another cause of World War I were War Plans Germany knew France was angry about the Franco-Prussian War. They knew France would probably invade Germany at some point. So Germany drew up a plan for war against France called the Schlieffen Plan. What did the Schlieffen Plan say?

The Schlieffen Plan said that if France attacked, they would probably have allies, and that would most probably be Russia. The plan said that Germany could not win a war with attackers on each side, called a two-front war, so they would need to knock France out of the war quickly, then turn their entire military against Russia. If Germany slowed down and got trapped between France and Russia, their chances of winning any war would be very low But if they could take them one at a time, they thought they could win.

When France heard of Germany's war plans, they made one of their own: Plan 17 Plan 17 said France would take Alsace and Lorraine, then Germany's capital city. How would they do that? They were a little sketchy in that department. I did a Yahoo image search for Plan 17. Here’s what came up.

So, just before World War I breaks out, you have these European nations competing with each other for colonies, building up huge armies and navies, making plans to go to war against each other, and feeling certain that they are going to be attacked at some point.

So, in this climate of fear, the nations started reaching out for friends (allies.) Germany signed an agreement with their long-time friend, Austria-Hungary. France felt threatened and signed an agreement with the big boy of Europe, Russia. Italy then signed with Germany and Austria- Hungary. These three were known as the Central Powers. Great Britain then signed with France and Russia, creating the Triple Entente, or Allied Powers (Allies.)

The US was trading with all of these countries, and making quite a bit of money. They decided to remain neutral. And since they're 3,000 miles from Europe across the Atlantic Ocean, they thought they would be able to stay that way.

The spark that starts World War I comes in Remember Bosnia, that region owned by Austria- Hungary? That region that wanted to be free from A-H? That region that Serbia wanted? People are protesting in Bosnia against A-H, demanding to be independent. There are riots and violence.

So the emperor of Austria- Hungary, Franz Joseph, sends his son, Franz Ferdinand, the archduke (or prince) to Bosnia to quiet the protests. While driving through Sarajevo, the capital of Bosnia, Archduke Franz Ferdinand, heir to the Austrian throne, was shot and killed by Gavrilo Princip. He was a member of a terrorist group called the "Black Hand." He was from Serbia.

"I am a Yugoslav nationalist, aiming for the unification of all Yugoslavs, and I do not care what form of state, but it must be free from Austria." —Princip, during his trial in "No I am not sorry. I have cleared evil out of the way" —during his trial "If I hadn't done it the Germans would have found another excuse." —Supposedly his last words. "I am not a criminal, for I destroyed a bad man. I thought I was right." —after he performed his assassination "No I am not sorry. I have cleared evil out of the way" —during his trial

Enraged at the death of his son, Emperor Franz Joseph declares war against Serbia. Serbia's ally and "Father Country," Russia, then declares war on Austria-Hungary. Then the ally of A-H, Germany, declares war on Russia. Russia's ally, France, declares war on Germany. France's ally Great Britain declares war on Germany. And then, Germany's ally Italy turns on them and sides with France, declaring war on Germany.

So that system of alliances turned what should have been a tiny little conflict between Austria-Hungary and Serbia into World War I. The US was still neutral.

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