We were in WW I for the money. It wasn’t our war, it was the war of the Royals. Millions of lives lost for Kings and Princes and their greed. One comment about their prisoners here were treated better than ours were in Germany reminded me of a coworker I had. He was captured during the Bulge, they weren’t cruel to him, his only complaint was the food as a PW. He knew that food was scarce while he was a POW, even the Germans complained, however they got what ever the Germans were getting. In 1945 Germany they were lucky if there was anything left that was edible. The PWs here had southern fried chicken and an abundance of other items, because we had them, there was no real food shortage. Heck we even fed the Soviet army. During WW II my parents were refused food at the corner store because the name sounded German and my mom was an Italian. Pop was Scandinavian, the store owner was a complete jerk with a German sounding name but of English or Irish background. In WW II if they locked up all the American Italians and Germans, who would be left fight the war?
If I recall correctly, Eisenhower, Nimitz and Halsey were of German ancestry.
The Germans, during WWII, generally followed the Geneva Convention in handling of American, British, Canadian and French prisoners of war. Unless they were Jewish. Not so much if the prisoners were Russians.