During his early diplomatic activities in Bulgaria he saved Bulgarian Jews by issuing Taufzertifikaten and travel permits to Palestine 's life. In 1922 he was Titular Archbishop of Thebes.
From 1944 to 1945, he contributed greatly to the bailout of neutral countries (Portugal, Spain, Sweden, Switzerland and Vatican City ) and the International Committee at ( initiated by Carl Lutz, led among others by Giorgio Perlasca, Friedrich Born of the Red Cross in Budapest, Raoul Wallenberg, Angel Sanz Briz ). He exhibited more than 15,000 letters of protection and Taufzertifkate to Hungarian Jews. As Doyen of the Diplomatic Corps, he protested vehemently at several times the Hungarian government against the deportation of the Jews. (see also the extermination of the Hungarian Jews, History of the Jews in Hungary)
1957 moved Rotta back from the diplomacy. In 1997 he was honored by Yad Vashem as Righteous Among the Nations.