A World War I timeline

The great war

Rise of powers

Positioning for conflict

A shot triggers war

Battle begins

War on land and at sea

Air raids and trenches

Airships, submarines, and poison gas

A deadly spring

British retaliation

Battle goes to sea

Extreme casualty

Hints of a turning tide

Raids in the air

Russia falls, Germany regroups

Germany hangs on

The U.S.A. arrives

Central powers weaken

Collapse of German forces

Nations fall and rise

Consequences of war.