The Roaring Twenties, jazz music, Hollywood glamour: the end of the First World War ushered in a golden age for America, with a booming stock market and rampant property speculation. It seemed as if the good times with Presidents Harding and then Coolidge in charge would never end. In marked contrast were the fortunes of many European countries, struggling to repay war debts and with the terms of the Treaty of Versailles plunging Germany into economic...