The currency reform of 1948 changed West Germany’s money overnight. From 21 June 1948, only the new Deutsche Mark was valid. The details had been worked out in secret. From 21 April to 8 June 1948, eleven German financial experts met in a closed building in Rothwesten near Kassel, behind a fence guarded by US military police. For 49 days, they drafted the regulations and the logistics of the reform. On the Allied side, most of the work was done by Edward Tenenbaum, who was 27 years old.