Dreams of a final theory: the failed electromagnetic unification and the origins of relativity

At the end of the 19th century, efforts were made by several researchers to build up a unified foundation for the whole of physics, grounded solely on electromagnetism. Some of the concepts usually associated with relativity were actually born in this context, before 1905. The main features of these pre-Einsteinian theories are briefly presented, and their interaction with relativity is discussed, by virtue of which ideas originated in a largely different frame were adapted and somehow incorporated into the new theory.