net import of gold meant that the foreign demand for American currency to purchase goods, services, and investments exceeded the corresponding American demands for foreign currencies. In the final years of the greenback period (1862–1879), gold production increased while gold exports decreased. The decrease in gold exports was considered by some to be a result of changing monetary conditions. The demands for gold during this period were as a speculative vehicle, and for its primary use in the foreign exchange markets financing international trade. The major effect of the increase in gold demand by the public and Treasury was to reduce exports of gold and increase the Greenback price of gold relative to purchasing power. Abandonment of the gold standard Impact of World War I Governments with insufficient tax revenue suspended convertibility repeatedly in the 19th century. The real test, however, came in the form of World War I, a test which "it failed utterly" according to economist Richard Lipsey. The gold specie standard came to an end in the United Kingdom and the rest of the British Empire with the outbreak of World War I. By the end of 1913, the classical gold standard was at its peak but World War I caused many countries to suspend or abandon it. According to Lawrence Officer the main cause of the gold standard's failure to resume its previous position after World War I was "the Bank of England's precarious liquidity position and the gold-exchange standard". A run on sterling caused Britain to impose exchange controls that fatally weakened the standard; convertibility was not legally suspended, but gold prices no longer played the role that they did before. In financing the war and abandoning gold, many of the belligerents suffered drastic inflations. Price levels doubled in the U.S. and Britain, tripled in France and quadrupled in Italy. Exchange rates changed less, even though European inflation rates were more severe than America's. This meant that the costs of American goods decreased relative to those in Europe. Between August 1914 and spring of 1915, the dollar value of U.S. exports tripled and its trade surplus exceeded $1 billion for the first time. Ultimately, the system could not deal quickly enough with the large deficits and surpluses; this was previously attributed to downward wage rigidity brought about by the advent of unionized labor, but is now considered as an inherent fault of the system that