In The Great War, the Americans were led by Black Jack Pershing with his quarter of a million men who arrived in 1917. More were to follow.
The Germans were completely stretched on the Eastern Front with Russia - even if that was to become a lesser problem after the Russian Revolution.
The Germans were stretched on a 500 mile frontier from Belgium to the Swiss border on the Western Front.
Consider this map.
Did nobody consider that these new, although admittedly not battle-hardened, 250,000 soldiers, might have landed on the British East Coast to muster rapidly - and then, under the protection of the world's biggest navy - travelled full steam ahead to the under-protected areas of Bremerhaven and Hamburg in order to open up a third front? Germany would have been split into two and it would have concentrated their minds, wonderfully.
Germany would have been forced to pull vital troops out of defensive lines in both the East and The West.
There may have been valid reasons for not having launched this surprise attack but I am unable to discover them.
Instead, the Americans were simply used to boost the allies in France.