On 10 December 1956, Hendrik Oosterhuis, Chairman of the Dutch Trade Union Federation and member of the Action Committee for the United States of Europe (ACUSE), sends a letter to the Foreign Ministers of the six countries participating in the Intergovernmental Conference on the Common Market and Euratom in Val Duchesse in which he emphasises the importance that he places on the association of European trade unions with the operation and social aspects of the future European Economic Community (EEC) and European Atomic Energy Community (EAEC or Euratom), in particular through the establishment of an Economic and Social Committee (ESC).