Militarism is a belief that nations should have the right to a strong military that can be used to defend themselves and intervene during times of crisis if needed. Examples of militaristic nations include the Third Reich, North Korea and the United States.

A reason why Militarism was so effective and prominent in this time period was the often very blatant glorification of war. Often times, young men would see these glamorous propaganda posters urging them to enlist and help defend their countries against their enemies, whoever those may be. As a result of this intense patriotism, a lot of citizens supported the war efforts and generally supported militaristic governments and elected officials. This was most prominent during World War I and II.

"Help Uncle Sam stamp out the Kaiser!" "Buy U.S govt bonds" A propaganda poster used in WWI

The Irish Guards, an all Irish Regiment of the British Army. This poster captures the glorification of the soldier with the caption: "1 Irishman defeats 10 Germans".

The period leading up to World War I was a time that saw great increases in military spending in large and wealthy nations. Britain, France, Austria-Hungary, Germany, and Russia to name a few all increased their military spending in the 40 years leading up to the First World War. Germany especially invested in their military as they increased their spending by 73% between 1870 and 1914! Not only did this rapid increase in spending make nations extremely powerful, but it also caused great fear. Britain for instance, feared that because the Germans were upgrading their naval fleet that a naval invasion of Britain was feasible.

Nationalism is defined as an ideology in which one is loyal to their country and puts it's interests before any others. Nationalists often have extreme patriotism and are willing to do anything for their country regardless if their actions are right or not. A lot of nations in the present day were formed because Nationalists were tired of a dominant power dictating their actions (colonies and empires) and wanted to have their own freedoms and civil liberties. But in the period leading up to WWI, nationalism was causing great tension especially among ethnic groups and colonies wanting to break away and become their own nation.

A lot of ethnic groups like the South Slavs felt alienated and felt discriminated against and oppressed under the Austro-Hungarian and Ottoman Empires. As a result of this environment, ethnic nationalism flourished within the South Slavic minority. This, in turn, caused ultra-nationalists groups like the Black Hand to become increasingly popular and hostile.

While all this tension was brewing a new threat emerged, The Black Hand and nationalistic terrorism. The Black Hand was a Serbian ultra nationalist group lead by Dragutin Dimitrijević or "Apis". It's primary goal was to unify Serb and other South Slavic territory under the control of Austria-Hungary into one country along with Serbia similar to Yugoslavia. On the 28th of June 1914, the Archduke of Austria-Hungary Franz Ferdinand was assassinated by a member of the "Young Bosnia" Gavrilo Princip. Princip who was associated with the Black Hand, killed the Archduke in a show of terror that ultimately caused the July Crisis. This one incident directly lead to the beginning of the First World War.

Imperialism is defined as extending a nation's power through either diplomacy or military force. Leading up to WWI, these large empires like the British, German and Russian empires began to lose their power and influence around the world. Due to the aggressive imperialism at the time, These empires along with the Austro-Hungarian and Ottoman Empires were increasingly headed to war which began with WWI. By the end of the war, the German, Russian, Austro-Hungarian and Ottoman Empires all collapsed while the British Empire gained more influence as a result of the Entente's victory.

Imperialism was a major cause of WWI because of two things, land and resources. A lot of these empires wanted more land from other countries so that they could use that territory gained for their own national interests. The same thing really applies with resources. However, the way empires were willing to achieve their imperialistic goals really makes it seem that WWI was inevitable. Imperialism caused these countries to aggressively attempt to annex territory and threaten war if demands aren't met. This in turn lead to a lot of tension between the largest empires.

Alliances are associations between one group and another. This is especially true when talking about alliances between countries. In World War I there were 2 major alliances, the Triple Entente and the Triple Alliance (some may refer to these countries as the Central Powers). The Triple Entente consisted of Britain, France, Russia (until 1917) and their allies. The Triple Alliance consisted of the German Empire, Austria-Hungary, the Ottoman Empire and their puppet states and colonies.

Often times alliances can be very good things, that is if their are stable. A key aspect as to why fragile alliances caused World War I was that many of these countries who signed these alliances and were suddenly drawn into a World War were often poorly trained and armed. A lot of these countries also didn't want to go to war but due to agreements when forming these alliances, they were pretty much forced to fight.

The assassination of Archduke Franz Ferdinand really showed how weak and destabilizing these alliances were. Because his assassin was a Serbian ultra nationalist, Austria-Hungary formally blamed Serbia for the incident. Since Serbia was also allied with Russia, France, the United Kingdom and other countries, when Austria-Hungary declared war on 28 July 1914 and called their allies, all these countries which made up the two alliances were drawn into a war and ultimately had to declare war on the opposite side regardless of any previous relationships.