After the Allied victory in WWI, the leaders of the US, UK and France imposed harsh peace terms on the defeated Germans. Germany (and the other defeated Central Powers) had to make reparations to the Allied countries.
The problem was that the payments that the German government was supposed to make were so great that they would bankrupt the country. Due to German unwillingness and inability to service the payments the Allies resorted to military measures such as the occupation in 1923 of the Ruhr industrial area.
In order to defuse the situation and find a realistic solution to the reparations problem the Dawes Plan was implemented. Allied troops would leave the Ruhr area and the German government would resume payments, after receiving a US loan that would revitalize the German economy.
In Germany the Allied representative responsible for monitoring the German compliance with the Dawes plan was mr Seymour Parker Gilbert and his official title was Agent General for Reparations by the Allied Reparations Commission.
It seems that the German government closely monitored Gilbert’s communications and was able to solve some of his encrypted traffic to New York (Federal Reserve bank), Paris and Rome.
Documents of the German Foreign Ministry’s decryption department Pers Z, captured at the end of WWII, show that his messages were solved by the German codebreakers:
Source: TICOM report DF-15 ‘Reports of Group A’ (US National archives - RG 457)
Additional information: Gilbert’s 1927 report.