Number in order the events that started World War I.

Question

Germany declared war on Russia and France.
Serbia refused to accept Austria's ultimatum.
Great Britain declared war on Germany after German troops violate Belgian neutrality.
Archduke Franz Ferdinand was assassinated.
Additional warring factions aligned with either Central Powers or Allied Powers.
Russia mobilized its army.
Italy signs a secret treaty with Great Britain, and eventually joins the Allied Powers.
Austria declares war on Serbia.

Answer 1

1. Archduke Franz Ferdinand was assassinated.
2. Austria declares war on Serbia.
3. Serbia refuses to accept Austria's ultimatum.
4. Additional warring factions align with either Central Powers or Allied Powers.
5. Russia mobilizes its army.
6. Germany declares war on Russia and France.
7. Great Britain declares war on Germany after German troops violate Belgian neutrality.
8. Italy signs a secret treaty with Great Britain and eventually joins the Allied Powers.