I can't give a definitive answer to your question. I can, though, tell you two things about my own situation. Perhaps the last one will help.

First, my Bergens are from Ireland....that's been pretty well confirmed. Second, in my tree are von Kreinerts. My g-grandfather was born in 1845 in Trier, Germany. When he migrated to the U.S., the name was shortened to Krein. Why? Don't know his reasoning. From my knowledge of history I know there was a lot of hatred toward Germans in the U.S., especially during World War I. Many Germans changed their names so they wouldn't stand out as Germans.

Hope this is of some help.

Good hunting.

Rich