It is frequently stated in the literature that the first attempt to unify gravitation and electromagnetism through a theory in higher dimensions was attempted by Kaluza and Klein. Yet, today I have realized that this is not true. The first such attempt was done by Nordstrom in 1914 http://arxiv.org/abs/physics/0702221 BEFORE Einstein constructed his general theory of relativity. The idea is surprisingly simple. It is a Maxwell theory in 5 dimensions, with the ansatz that the 5-component vector potential does not depend on x_5. With this ansatz the 5-dimensional Maxwell equations split into the 4-dimensional Maxwell equations and a scalar 4-dimensional theory of gravity described by A_5. This theory can also be viewed as a first version of a brane theory (which are today popular in the context of string theory). By contrast, the Kaluza-Klein theory is a first compactified theory (which are also today popular in the context of string theory).