Assassination of Archduke Franz Ferdinand of Austria, heir to the Austro-Hungarian throne, who was killed in Sarajevo along with his wife Duchess Sophie by Bosnian Serb Gavrilo Princip.

Austria-Hungary seeks German support for a war against Serbia in case of Russian militarism. Germany gives assurances of support.

The Russian offensive in the Carpathians begins. It will continue until April 12.

Battle of Jassin.

Austro-Hungarian offensive against Montenegro, which capitulates.

Battle of Mojkovac.