From 1921 to 1926 he studied piano with Franz Schreker and Walther Carl Meiszner in Berlin[1] and with Ermanno Wolf-Ferrari in Munich.
Early on he became famous accompanying singers such as Erna Berger, Corry Nera, who in 1934 on became his wife, and Hermann Prey.
In 1933 he was recruited as a music specialist for the German Theater by Max Reinhardt, since Lothar was a member of the Kampfbund für deutsche Kultur, an antisemitic organization forming part of the Völkisch movement.
[2] One year later he became the musical director of the Prussian State Theater in Berlin thanks to Gustaf Gründgens.
He was also renown as a composer of theater and film music (e.g. form Friedemann Bach, Holiday in Tyrol and Faust by Gustaf Gründgens) and of songs to text from Hermann Löns, Hermann Hesse, Joachim Ringelnatz, Christian Morgenstern and other German poets.