Proper Names

Q. What is the best way to use a possessive with royalty that commonly has extra descriptors after their name? E.g., Philip II of Macedon; Alexander the Great; Elizabeth I; or Gregory I, “the Great.” Sometimes the number or descriptor has become part of the individual’s name. I couldn’t find this easily on the website so I am asking. Any help is much appreciated.

A. If the numeric suffix or description follows the name with no intervening punctuation, simply add an apostrophe and an s: Philip II of Macedon’s son; Alexander the Great’s mother; Elizabeth I’s reign. But if a comma (or parentheses) or quotation marks intervene—as in the case of a description that follows a numeric suffix—you will want to rephrase: not Pope Gregory I, “the Great’s” predecessors, but the predecessors of Pope Gregory I, “the Great.” For more on such names, see CMOS 8.34.