Question

what was considered an act of war in 1914?

Answer 1

The assassination of the archduke of Austria-Hungary by a Serbian named Gavrilo Princip that was part of the Young Bosnia, a terrorist organization that wanted to end the A-H rule in B & H.

Answer 2

European armies doubled between 1890 and 1914. This mobilisation and process of assembling troops and supplies and making them ready for war was considered an act of war in 1914. This was ordered by Czar Nicholas II (of Russia), against Austria-Hungary