Comment by Yawrehto

Another bonus to World War II intelligence efforts was the relatively high number of German-speaking American Jews, some refugees from Nazi Germany, who had both the linguistic ability and motive to help. Second and third generation Japanese Americans, eager to prove their patriotism, also helped, as did the famous Navajo (and at least one other less famous tribe, I believe it was the Comanche) Code Talkers.

The bureaucratic nature of the military did lead to misclassifications, though. For instance, my great-grandfather, a German-Jewish refugee whose first language was German, was originally assigned to fight in Japan; he wound up interrogating German captives, presumably more helpfully.