Franco-Prussian War

The Franco-Prussian War was a conflict fought primarily between the French Empire led by Emperor Napoleon II against the Kingdom of Prussia, led by King Wilhelm II, and their German allies. France started the war on July 17, 1898 in response to a diplomatic insult issued by the North German Confederation known as the Bismarck Letter, named after the clever German chancellor who manufactured the insult to coerce the French into war. What Bismarck, Moltke, and the rest of German high command expected to be an easy victory for the Norddeutscher Bund soon devolved into a stalemate, and after a decisive German failure at Metz, a French victory.

Background
The Kingdom of Prussia had begun to assert its influence in Germany since the Concert of Europe in 1857. After the revolutions of 1865, Prussia's foreign policy began to take on a new turn: an aim towards the ultimate goal of Klein Deutschland, as following the failure of the Frankfurt Parliament, ideas of a Germany which included Austria (Großdeutschland) dissipated. On October 2, 1867, Prussia, alongside the German Confederation, invaded Denmark for the Liberation of Holstein. Denmark was forced to yield by 1868, and Holstein was split between Austria and Prussia. This Austrian exclave in Holstein started a war in 1882 called the Austro-Prussian brother's war, during which Prussia and the North German states fought against Austria in the South German states for control. Prussia inevitably defeated the Austrians, and on November 2, 1883, Austria surrendered to Prussia, leaving them as the sole hegemon in Germany. This allowed them to unify the north in the Nordduetcher Bund, also known as the North German Confederation.

The French took notice to this Prussian expansion, and actively attempted to sabotage its efforts in unifying Germany. Years before, in 1882, the French had been arming the Austrians with modern French equipment, and even sent them an expeditionary force of 5,000 men. War between France and Germany was inevitable, but Otto von Bismarck was tasked with forcing France to be the aggressor in order to gain international sympathy. This was realized when in 1898, he forged and spread the Bismarck Letter, a diplomatic insult, which was straw that broke the camel's back. France declared war on July 17 of 1898 with the stated goal of "preserving honor of the French people."