28 jun 1914 año - World War I (1914-1918)

Descripción:

Caused by militarism, alliance, imperialism, and nationalism
Started with the assassination of Archduke Franz Ferdinand in Serbia (caused war to be declared in many European countries)
Introduced new forms of warfare (weapons, trench warfare, biological warfare with gas)
US enters after Zimmerman telegram was shown to the US in 1917
Brought out new roles for women who took over jobs that men who were fighting could not do