From Hundred Days: The Campaign That Ended World War I, by Nick Lloyd (Basic Books, 2014), Kindle Loc. 2489-2509:
At first glance the doughboys looked little different from their British and French associates. They wore a version of the British tin helmet and used the small pattern box respirator. They ate bully beef. They fired French or British weapons, often Lee Enfields, Lewis guns or Chauchats, and threw Mills bombs. They went into action alongside French tanks – Renaults or Schneiders – flew French or British aircraft – Spads or Sopwith Camels – and grew to love the French 75mm field gun, the legendary soixante-quinze. But in other respects the Americans were remarkably different. While both British and French Armies recruited mainly from remarkably cohesive home societies (excepting, of course, their colonial contingents), Pershing’s men were drawn from the full spectrum of US society, and included many recent immigrants from Europe, Russia and Latin America, as well as Native Americans. A considerable number of black Americans also went to France, and although they were not permitted to serve alongside white soldiers and continued to suffer horrific racial prejudice, they did yeoman service on the lines of transport in France, helping to unload equipment and supplies, and doing the menial jobs without which Pershing’s army could not have survived.
The Americans were different in other ways too. They were much richer than their cousins in other armies. They could draw $30 a month, about ten times the pay of a French private, thus gaining the eternal jealousy of the poilus, who looked upon the arrival of the Americans with concern and insecurity. And in another odd, but still tangible way, the Americans differed from their British and French counterparts. They were big; physically big. Numerous commentators at the time noticed the physical presence of the first US soldiers, tall, well-built troops with high morale and an instinctive, almost cocky pride; the kind of soldiers that had not been seen on the Western Front since 1916, when Britain’s New Armies had entered the fray. For their commander, this was the key point. Pershing was confident that American valour – her aggressive frontier spirit – would be the answer to the stalemate in the west. When he had first travelled to France and met British and French commanders, Pershing had quickly come to the conclusion that their methods would never win the war. They were stuck in their ways, he would tell his subordinates, and obsessed with limited, artillery-heavy trench attacks. He wanted his troops to be trained, first and foremost, as individual soldiers and riflemen, able to think for themselves on the battlefield and engage the enemy on their own terms.