On March 1971, European Commission accepted Werner Plan which would take the countries of the Common Market to economic and monetary union. Countries agreed to stabilize fluctuations of their own currencies between each other within the scope of Werner Plan. Exchange rate movements of European currencies lessened (snake), remained big relatively against Dollar too (tunnel) Therefore this system took the name of “snake in the tunnel”. In December 1971, the countries (Groups of Ten) comprising Belgium, Canada, France, Germany, Italy, the Netherland, Sweden, Swiss, England and USA convened in Smithsonian Institute in Washington and made Smithsonian agreement. With this agreement, value of USA Dollar was decreased 8% against monies of main foreign countries. But in short time, insufficiency of this devaluation rate in American Dollar appeared. New 10% devaluation was made on 12 February 1973 against speculative attacks to Dollar. However speculative movements were so extensive, foreign exchange market had to be closed between 1 March- 18 March 1973. When foreign Exchange markets were opened again on 19 March, Japan and main European currencies were left to free float against Dollar. Although this was considered as temporary arrangement in the beginning, a new period- period of flexible currency system started.