Of the following World War 1 related events, which happened last?
German declaration of war on France.
Germany pledging its support for Austria-Hungary.
Russia pledging its support for Serbia.
German invasion of Belgium.
The events in chronological order are:
1. Germany pledged its support for Austria-Hungary.
2. Russia pledged its support for Serbia.
3. German invasion of Belgium.
4. German declaration of war on France.
Therefore, the German declaration of war on France happened last.
In chronological order, the World War 1 related events would be:
1. Germany pledging its support for Austria-Hungary.
2. Russia pledging its support for Serbia.
3. German declaration of war on France.
4. German invasion of Belgium.
Therefore, the event that happened last among the options given would be the German invasion of Belgium.