When the USA entered World War I in April 1917 her Regular Army counted just 128,000 men and lacked all the necessary equipment and training for modern trench warfare. By the Armistice of November 1918, General John J.Pershing's American Expeditionary Force in France had more than 2 million men and was holding 25 per cent of the Western Front. They had helped smash Ludendorff's brilliant Operation "Michael" in the lines before Paris; had turned onto the offensive themselves at St Mihiel and the Meuse-Argonne; and if Germany had not negotiated peace with unexpected speed the US Army would have...