After discharge from the service, from 1919 to 1923 he worked as a commercial clerk and iron dealer in Halle and Ilmenau.

[1] In November 1922, Marschler joined the Nazi Party and became a member of the Ilmenau Ortsgruppe (Local Group) headed by Fritz Sauckel.

After the Nazi seizure of power at the national level, Sauckel was appointed to the newly created position of Thuringian Reichsstatthalter (Reich Governor) and Marschler succeeded him as Minister-President of Thuringia on 8 May 1933 while also retaining the portfolios of Finance and Economics.

[4] After the dissolution of the Landtag in October 1933, Marschler went on to be elected as a member of the Reichstag from electoral constituency 12, Thuringia, in November 1933 and would retain this seat until May 1945.

After Fritz Wächtler left the State ministry on 22 January 1936, Marschler also took on the portfolio of Minister of Education.

A holder of the Golden Party Badge, Marschler remained at the head of the Thuringian State government through the end of the Nazi regime.