Friedrich was the boy who whipped the dog in Struwwelpeter. I'm guessing, though, that his parents misnamed him in the book, due to the name's meaning.
Friedrich was the name of three sons of King Frederick William I of Prussia and his wife Sophie. 1. Friedrich Ludwig (1707-1708) 2. Friedrich Wilhelm (1710-1711) 3. Friedrich (1712-1786).
Friedrich (1720-1721) was the oldest son of Augustus III of Poland and his wife Maria Josepha. This was also the name of his younger brother (1722-1763).
Friedrich was the real name of director Fritz Lang (1890-1976).
― Anonymous User 1/14/2009
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Friedrich was used as the name of the eldest von Trapp son in the movie "The Sound of Music". Friedrich's character represented the real eldest son (who was in fact the firstborn child, not the second), who was named Rupert.