Vietnam and Cambodia
The Allies.
American troops were used in Russia during there revolution along with English troops fighting on the side of the whites defending the Czar against the reds.
1917
Soviet (Russian) troops were primarily engaged fighting the Germans along the eastern front and into Berlin.
Vietnam shifted the burden of the ground fighting from American troops to South Vietnamese troops during the later stages of the war. This was called "Vietnamization".
Luxembourg lost the least troops during the First World War.
“Doughboys” became the nickname for the troops of General John Pershing's American Expeditionary Forces, who traversed the Atlantic to join war-weary Allied armies fighting on the Western Front in World War I.
Around 16 Million US troops were deployed during World War 2.
In France, Belgium, etc. ... the Western Front.
Europe
no one