Having had a look at the electrification history of Germany/Austria, some interesting facts emerged:
- the first electrified line in Germany was the Murnau-Oberammergau line in Bavaria, in 1905 (5kV 16⅔ Hz AC, later converted to the standard 15kV)
- Munich-Garmisch-Mittenwald-Innsbruck was planned for electrification by 1914, but completion was delayed until 1925
- Munich-Salzburg/Kufstein followed in 1928 and Munich-Augsburg-Ulm-Stuttgart in 1933
Austria made a strategic decision to electrify its main lines after WW1, because its coal reserves were by then largely in Czechoslovakia.
They started in the west, with the Arlberg route in 1924-25, and the Brenner in 1929-34. Routes to Innsbruck were electrified by 1930, and the Tauern route by 1935.
Work on the Westbahn from Salzburg to Attnang-Puchheim was complete by 1941, but Vienna was not reached until 1952.
Meanwhile back in Germany, there were experiments with electric traction between Leipzig and Dessau before WW1, but services to Halle started in 1922 and to Magdeburg in 1934.
The railway wanted to begin with electrifying around Trier (Mosel) or Altona-Kiel (Hamburg), but the army insisted they start near the coalfields around Leipzig for strategic reasons.
Apparently the Dessau route was electrified 3 times: pre-WW1; in the 1920s after the equipment had been taken for war use; and again in the 1960s to restore the route after Soviet reparations.
The link between Leipzig and Munich via Jena, Nuremburg and Augsburg was completed 1935-39.
It's curious there was no pre-WW2 electrification in the Rhine-Ruhr industrial area, which was generally wired in the late 50s and 60s.
However, it is where much of Germany's coal reserves are located.
There was also 3rd rail electrification in this period for the localised Hamburg (from 1907) and Berlin (from 1924) S-Bahn systems.
Berlin was not connected electrically to the west German network until the modernisation/rebuilding of the 4 main lines to the west following reunification.
The Frankfurt route via Erfurt and the Munich route via Jena were wired in 1995, with the Hanover (Lehrte) and Hamburg lines following in 1997.
The Munich route via Jena has just been replaced by the high-speed NBS via Erfurt.