Truman might have understood the dark intentions of the Soviet Union, but many leading American liberals, such as FDR’s former vice president, Henry Wallace, and his widow, Eleanor Roosevelt, still affectionately referred to the Communist dictator Stalin as “good old Uncle Joe.” It was difficult for Americans, in the space of a few months, to go from regarding the Soviet Union as our ally in war to a potentially lethal enemy. Much of the liberal press was trying to drive a wedge between the U.S. and Britain, while rightwing isolationists opposed any long-term American alliance with European nations.
Expecting that the German offensive would develop along much the same lines as it did in 1914, the lines of communication of the British Expeditionary Force (BEF) did not run through the "short crossing" Channel ports – Boulogne, Calais, Dunkirk, etc. – but rather through Dieppe and Le Havre. On 13 May, the Wehrmacht's attack through the Ardennes had reached the Meuse River at Sedan and then crossed it, breaking through the defences of the French Army. By 20 May, Wehrmacht armoured divisions had reached the coast of the English Channel, splitting the BEF and the French First Army from the main French forces.