Truman appointed Byrnes as Secretary of State on July 3 , 1945 . As Secretary of State , he was first in line to the Presidency as there was no Vice-President during Truman 's first term . He played a major role at the Potsdam Conference , the Paris Peace Conference , and other major postwar conferences . According to historian Robert H. Ferrell , Byrnes knew little more about foreign relations than Truman . He made decisions after consulting a few advisors , such as Donald S. Russell and Benjamin V. Cohen . Byrnes and his small group paid little attention to the State Department experts and similarly ignored the President
Potsdam Conference
Potsdam Conference
James F. Byrnes