The Second French Empire was the 18-year Imperial Bonapartist regime of Napoleon III from 14 January 1852 to 27 October 1870, between the Second and the Third Republic of France.

Napoleon III liberalised his rule after 1858. He promoted French business and exports. The greatest achievements included a grand railway network that facilitated commerce and tied the nation together with Paris as its hub. This stimulated economic growth and brought prosperity to most regions of the country. The Second Empire is given high credit for the rebuilding of Paris with broad boulevards, striking public buildings, and elegant residential districts for upscale Parisians.

In international policy, Napoleon III tried to emulate his uncle Napoleon I, engaging in numerous imperial ventures around the world as well as several wars in Europe. He began his reign with French victories in Crimea and in Italy, gaining Savoy and Nice. Using very harsh methods, he built up the French Empire in North Africa and in Southeast Asia. Napoleon III also launched an intervention in Mexico seeking to erect a Second Mexican Empire and bring it into the French orbit, but this ended in a fiasco. He badly mishandled the threat from Prussia, and by the end of his reign, the French emperor found himself without allies in the face of overwhelming German force. His rule was ended during the Franco-Prussian War, when he was captured by the Prussian army at Sedan in 1870 and dethroned by French republicans. He later died in exile in 1873, living in the United Kingdom.