More than three million American men, many of them volunteers, joined the A.E.F. in the first 20 months of US involvement in the First World War. Of these, over 50,000 were killed on European soil. These were the Doughboys, the young men recruited from the cities and farms of the United Sates, who travelled across the Atlantic to aid the allies in the trenches and on the battlefields. Without their courage and determination, the outcome of the war would have been very different.