Two countries promise to defend each other if one is attacked
Alliances
A British ship was sunk by Germany and killed Americans
Lusitania
Germany attacked ships and killed Americans
Unrestricted submarine warfare
A country starts building up its army and stockpiling weapons because it fears war
Militarism
A secret message asking Mexico to attack the U.S.
Zimmermann Telegram
The US had strong economic ties with this side
The Allies
A country takes over land in Africa to gain resources and power
Imperialism
The assassination that started the war
Assassination of Archduke Franz Ferdinand
Germany had strong ties with this side
Central Powers
One country is attacked, and suddenly multiple countries join the war because of agreements
Alliances
The fighting style where soldiers lived in dugouts for months
Trench warfare
Woodrow Wilson proposed this after the war
14 Points
People in a country believe they are better than others and want to prove it
Nationalism
Great Britain, France, Russia, and the US
This new organization was created to keep peace
League of Nations