The development of the so-called Einheitslokomotiven (= Standard electric locomotives) dates back to the 1950s, when the then German Federal Railways needed successors for their pre-war electric locomotives. The aim was to build different locomotive series for long-distance trains, local transport and heavy freight trains, but as many parts as possible should be interchangeable. A total of more than 1,500 locos were built. Meanwhile, almost all engines were withdrawn.