Over the course of the nineteenth century, a popular nationalist movement developed in the German states that had gained considerable strength by 1871, the year of unification. The German gymnastics association movement was one of the main forms in which popular nationalism was organized. It was started by Friedrich Ludwig Jahn early in the nineteenth century as a means to train young Germans to fight the French occupation. Gradually, it developed into a movement that sought to unify Germany, a project that was not, at first, supported by the German states. The movement was also guided by liberal and, especially before the revolution of 1848, democratic principles, and in this sense, too, was at odds with the reigning political system in Central Europe.