On 28 June 1914, archduke Franz Ferdinand of Austria, heir to the Austro-Hungarian throne, was assassinated in Sarajevo by Serbian nationalist Gavrilo Princip. The assassination provoked outrage and caused tensions to rise between the European powers. The murder ultimately triggered World War I, as it formed the basis of Austria-Hungary’s declaration of war against Serbia. In Europe, two fronts were formed as the Central Powers — including Germany, Italy and Austria-Hungary — locked horns with the Allies of World War I, i.e. France, Britain and Russia. In the course of the war, the two opposing alliances were joined by a number of nations. Belgium, as well as The Netherlands, was neutral at the beginning of the war.