After the war, Clausen studied medicine in Heidelberg and became a doctor in 1924, after which he returned to Aabenraa, which had been voted back to Denmark in 1920, and set up a practice.
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Two years later, Clausen ousted the leadership committee of the party (whose members were Einar Jørgensen, C. C. Hansen, and Cay Lembcke) from power and became the party's sole leader.
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Clausen's failure in the elections and his unwillingness to actively assist in forming a Danish branch of the Schutzstaffel alienated his German supporters, and as such SS Obergruppenführer Dr. Werner Best, the Plenipotentiary of the German Reich for Denmark, convinced Clausen to step down as leader of the party and replaced him with a three man committee shortly after his return to Denmark.
:For other people with the same or similar name, see Frits Clausen and Frederick G. Clausen.
Alf Clausen | René Clausen | Jimmy Clausen | Frits Zernike | Frits Staal | Frits Warmolt Went | Frits Clausen | Frits Bolkestein | Claus Lauritz Clausen | ''Winter at Simoa River''
Frits Thaulow | Sally Clausen | Jens Clausen | Frits Thaulow | Frits Philips | Frits Landesbergen | Erik Clausen | Donald H. Clausen | Claus Kristian Randolph Clausen | Charlie Clausen |
In February 1941 von Schalburg suggested to his friend, head of DNSAP Frits Clausen, the formation of a Danish SS unit, 'Regiment Dannebrog', to be commanded by himself.