There are likely two main figures named Friedrich Bruns you might be interested in:
Friedrich Christian Heinrich Bruns (1862-1945) was a German historian who specialized in the history of the Hanseatic League, a medieval trading confederation of Northern German towns. If you're interested in learning more about the Hanseatic League, Friedrich Bruns would be a good starting point for your research.
Friedrich Bruns (1853-1933) appears to have emigrated from Germany to the United States. Ancestry records suggest he was born in Hannover, Germany and died in Crabapple, Texas.
