On this day 155 years ago, on July 19, 1870 (June 21, 1870), the Franco-Prussian War broke out. In the late 1860s, all social forces opposing Napoleon III intensified their activities. Standing on the opposite side of the empire were not only the working class, but also the big Orleanist bourgeoisie, which was excluded from power by the Bonapartist faction, the industrial bourgeoisie and the petty bourgeoisie who advocated republicanism. Napoleon III had become the target of public criticism. He decided to use foreign war to get out of the domestic predicament. Empress Eugenie pointed to her son and said: "In order for this child to become emperor, war is necessary. "On the other hand, Napoleon III saw that Prussia had become the most powerful state in the German Federation, which was a major obstacle to maintaining France's superior position on the European continent, so he had to fight Prussia. For Prussia, defeating France was the key to its eventual unification of Germany, but Prussian Prime Minister Bismarck was very cunning. He needed war and wanted France to declare war first. The crisis of war finally arose due to a dispute between the two countries over the succession to the Spanish throne. In 1868, after the Spanish Revolution, Queen Isabella was abolished and the throne was suspended. To make France suffer from the enemy, Bismarck sent people to Spain, intending to buy the Spanish Parliament and the provisional government to make the cousin of the King of Prussia the king of Spain the king of Spain. Due to poor planning, the news leaked. In early July 1870, France protested to Prussia. In view of the fact that England, Austria, Russia, etc., also echoed this protest, King William I had to announce the disqualification of his cousin as a candidate for the Spanish throne. However, Napoleon III still ordered the French ambassador in Berlin to ask the king to guarantee that he would never agree to the Hohenzollern family's succession to the Spanish throne. Although the king refused to give such assurances, he reached a mutually acceptable agreement with the French ambassador. The king then telegraphed the results of the meeting to Bismarck. Bismarck was eager for war, and after consulting with the military personnel, he immediately tampered with the king's telegram, making it insulting to France, and published it to the embassies and newspapers of various countries. How could France tolerate this practice? Napoleon III thus declared war on Prussia first on July 19, 1870, and the Franco-Prussian War broke out.