World War One
Above are some of the reasons World War I started , there are some other reasons such as money when the Europeans needed financial support so we lent them money they never returned. Another reason is that's the Germans sunk the Lusitania (a passenger ship with obscured weapons in the lower level) which was carrying 128 a americans who unfortunately all died along with all the other passengers. All these reasons brewed in the minds of Americans along with the president at the time which persuaded him to write a letter to congress to give permission to enter the war , which the U.S later entered in 1917. With that said that's how Mania began.
Militarism is the process of enhancing a country's army and the pilling of weapons.
Alliances are agreements involving two countries to help each other during war.
Is an extreme love of your country which leads to feelings of elitism.
Imperialism is when a country with a stronger military take over a weaker country for natural resources.
The killing of Arch Duke Franz Ferdinand of Austria was an assassination which led to war between Serbia and Austria and later the United States.
The country in which The Duke was killed