In the period immediately following the Second World War, the disastrous effects of the isolationism of 1930-1945 were seldom denied in the western world. Politicians, economists, journalists proclaimed that the development of international commerce is one of the conditions for a nation's prosperity (Jean-Marcel Jeanneney, Pour un nouveau protectionnisme, Seuil, 1978, p.17). In France, most economists judged that the slump of the 1930s was due in great part to the protectionism instituted after the 1928 crisis that it was protection first by import taxes, then by exchange controls and restrictions, which caused a fall not only in imports but also in exports and in national production. Only a minority of such people considered protection as the consequence, not the cause, of the French crisis, rendered necessary by the obstinate refusal of the French to devalue the franc, as sterling was devalued in 1931 and the dollar in 1933. The accepted view was to have its effects on the developments of the following twenty years.