The branch of a nation's armed services that conducts military operations at sea.

A group of countries, political parties, or people who work together because of shared interests or aims.

1907 Alliance, linked France, Britain, and Russia.

1882 Alliance, linked Germany, Austria-Hungary and Italy.

The policy of extending the rule or authority of an empire or nation over foreign countries, or of acquiring and holding colonies and dependencies.

Identification with one's own nation and support for its interests, especially to the exclusion or detriment of the interests of other nations.

A cluster of nations in eastern Europe, between the Austro-Hungarian and Ottoman empires.

Heir to the Austro-Hungarian throne; his assassination by a Serbian national was the spark that started WWI.

Serbian nationalist terrorist organization.

The international crisis that began with the assassination of the heir of Austria-Hungary in Sarajevo on June 28, 1914 and culminated in the British declaration of war on Germany on August 4.

The military plan that required Germany to defeat France quickly to avoid a two Front war.