La Roche-sur-Yon is a commune in the Vendée department in the Pays de la Loire region in western France. It is the capital of the department. Its inhabitants are called Yonnais. The town expanded significantly after Napoleon I had chosen the site as the new préfecture of the Vendée on 25 May 1804, replacing Fontenay-le-Comte. At the time, most of La Roche had been eradicated in the Vendée Revolt (1793–96); the renamed Napoléonville was laid out and a fresh population of soldiers and civil servants was brought in.
Napoléonville was designed to accommodate 15,000 people. In 1854, La Roche was described in an English guide as "the dullest town in France".