WWI began when Austria-Hungary declared war on Serbia one month after:
- Serbia tried to take more of Austria-Hungary's land.
- Serbia burned their flag.
- Archduke Ferdinand and his wife were killed.
- Serbia won more Olympic medals.

The belief that a country should maintain a strong military capability and be prepared to use it aggressively to defend or promote national interests.

The term that relates to one country taking over another during the later half of the Nineteenth Century was?

The war might have involved only two nations, if not for

Nationalism

What was the name of the peace agreement signed to end World War 1?

This was a British Cruise ship (that had American passengers on it) that was torpedoed and sunk by a German submarine.