An impossibly complex web of alliances that maintained a fragile peace in Europe (and surprisingly held it together since the end of the Napoleonic Wars in 1815) always threatened to unravel. The 1914 assassination of Archduke Franz Ferdinand, the heir to the Austrian throne, by Serbian nationalists, made Austria declare war on Serbia. A doomsday machine kicked into gear: Russia mobilized against Austria. Germany mobilized against Russia. France mobilized against Germany. Germany prepared long-held plans to attack France.