Russia mobilizes its army in support of Serbia.

1 Aug.

When Russia refuses to accept a German demand to stop mobilization, Germany declares war on Russia. Switzerland, Sweden, Norway, and Denmark declare their neutrality.

2 Aug.

Germany, having occupied tiny Luxembourg, demands that Belgium allow the passage of troops across its territory, despite a Belgian declaration of neutrality.

3 Aug.

Germany declares war on France and launches an offensive through Belgium the following day.

4 Aug.

In response to Germany's violation of Belgian neutrality, Great Britain declares war on Germany. The United States declares its neutrality, and its 5 August offer to mediate the widening conflict is ignored.

5 Aug.

Montenegro declares war on Austria-Hungary.

Aug.

Austria-Hungary declares war on Russia.

8 Aug.

French and British troops mount an offensive against the German army in Lorraine.

12 Aug.

France and Great Britain declare war on Austria-Hungary. Italy is the only major European nation not yet engaged in...