Lesson 1: What was the International System like before 1914?
Great Powers, Europe in 1900, Britain, George V, British Empire, Germany, Kaiser Wilhelm II, Russia, Tsar Nicholas II, Austria-Hungary, Franz Joseph II, France, President Raymond Poincare, Ottoman Empire.
Lesson 2: How and why did the Alliance System form?
Alliances, Treaties, Collective Security, National Rivalries, Franco-Prussian War 1870-71, Otto von Bismarck, Wilhelm I, Dual Alliance 1879, Triple Alliance 1882, Franco-Russian Alliance 1894, Entente Cordiale 1904, Anglo-Russian Entente 1907, Triple Entente.
CrashCourse History: Nationalism
One of the major long-term causes of the First World War was nationalism. The growth in nationalism in Europe, especially after 1848 really defines the forces at work in Europe prior to the war. An understanding of what nationalism is will help you understand why countries were so willing to use war as a tool for achieving national priorities.
CrashCourse History: Imperialism
Another long-term cause of the War you need to understand is imperialism. One of the negative effects of nationalism was that it encouraged nation-states to think of themselves as different to others. This eventually led nation-states to think of themselves as superior to others thus the rise of nationalism in the 19th century led to, and worked in concert with, a growing desire to create global empires.