I am trying to see if any ancestors that immigrated from Germany in the 1800's were sent to the American interment camps during WWII. Is there a list of names for the Germans who were considered “enemy aliens”?
I'm sure that a number of German Americans were suspected of being pro Nazi during WWII. One of my grandmothers - of Irish and/or English ancestry - told me she moved to new house during WWII and her new neighbors saw all the pigeons around her house and wondered if they might be carrier pigeons and she got a visit from the FBI.
So certainly nervous, scared, excited, and/or patriotic Americans suspected a lot of German nationals and US citizens of German ancestry might be disloyal during World War II.
If someone emigrated from Germany in the 1800s, between 1800 and 1899, that would be at least 42 to 141 years before the USA entered WWII. So many of the Germans who emigrated to the USA in the 1800s would be dead by 1941, and many others would be old and feeble.
So only a minority of the Germans who emigrated from Germany in the 1800s would be alive and young enough to be considered a threat by the US government.
Furthermore, most of the Germans who emigrated to the USA in the 1800s became US citizens as soon as they could, and if they didn't their children, grandchildren, and great grandchildren, etc., probably would. I expect that only a small minority of German immigrants who had been in the country long enough to become naturalized citizens, and only a small minority of their descendants, were not citizens in 1941.
Internment of German resident aliens and German-American citizens occurred in the United States during the periods of World War I & World War II. During World War II, the legal basis for this detention was under Presidential Proclamation 2526, made by President Franklin Delano Roosevelt under the authority of the Alien and Sedition Acts.1
By the time of WWII, the United States had a large population of ethnic Germans. Among residents of the United States in 1940, more than 1.2 million persons had been born in Germany, 5 million had two native-German parents, and 6 million had one native-German parent. Many more had distant German ancestry. During WWII, the United States detained at least 11,000 ethnic Germans, overwhelmingly German nationals. The government examined the cases of German nationals individually, and detained relatively few in internment camps run by the Department of Justice, as related to its responsibilities under the Alien and Sedition Acts. To a much lesser extent, some ethnic German US citizens were classified as suspect after due process and also detained. Similarly, a small proportion of Italian nationals and Italian Americans were interned in relation to their total population in the US. The United States had allowed immigrants from both Germany and Italy to become naturalized citizens, which many had done by then. Wikipedia:Internment of German Americans
This lists a number of references and sources.
As a general rule an American citizen of German ethnicity would only be interned during WWII if suspected of being pro Nazi.
Undoubtedly there are lists of German nationals and German-American US citizens who were suspected, investigated, and/or interned during WWI and WWII.