Question: Wilhelmine Schröder was the royal mistress of a man that was King of Sweden beginning in what year?
Sentence (from "Charles XV of Sweden"): Though known as King Charles XV in Sweden (and also on contemporary Norwegian coins), he was actually the ninth Swedish king by that name, as his predecessor Charles IX (reigned 1604–1611) had adopted a numeral according to a fictitious history of Sweden.
Relevant evidence: No