The United States Army and Marine Corps began arriving in France in following the nation's declaration of war against Germany in April of the same year. The army formed the largest body of troops and consisted of three different organizations: eight Regular Army divisions, seventeen National Guard divisions and eighteen National Army divisions, formed by men drafted for national service.
Most of was spent training the troops in the US, transporting them to Europe, further training by our French and British allies and then taking over sections of the allied trench line as the units became ready for front line service.
The timeline below lists the major operations that the Americans participated in. It begins in late and early with small supportive roles to the British Army. By the late spring and summer, as the number of American units increased and were ready for combat, they fought with the French Army in defensive battles that ended the series of German attacks begun in March that were intended to defeat the allies.
American participation in the Champagne-Marne Operation, July , , is an example and is significant because it stopped the final German attack, put them on the defensive and marks the first allied attack that began the campaign that forced the them out of France and Flanders and for them to ask for an armistice in November American troops continued to serve with British and French armies up until the end of the war as shown in the list of operations.
However, as the US Army grew in size and experience it began to undertake its own major offensives such as the September , St. Each of these and the months of manning sections of the allied defensive line produced the casualties that Base Hospital 28 and other American Medical Department units were created to treat. Therefore, where data is available the numbers of casualties resulting from these specific periods of intense fighting are provided.
