However, we were told that Kathryn's maiden name was Frederiksen. Hugh was Firstman of Ilion on Aeneas. When, at the end of The Rebel Worlds, Hugh and Kathryn went into exile, her brother, Edward, succeeded to the Firstmanship and Ivar is his son.
Thus, despite the absence of Flandry and the McCormacs from The Day Of Their Return, we are dealing with Kathryn's nephew who is also the heir of Hugh's successor. Anderson writes a direct sequel but disguises it by changing the characters and even the surname of the Aenean first family.
He also introduces a completely new character, Chunderban Desai, who has, since the McCormac's exodus, been appointed High Commissioner of the Virgilian System, whose humanly colonized planet is Aeneas. Thus, the reader sympathizes both with Ivar trying to lead a new Aenean rebellion and with Desai trying to prevent it.
A commissioner is intermediate between a resident and a sector governor. Desai's superior is the Governor of Sector Alpha Crucis and the incumbent of that position has also changed since The Rebel Worlds. Desai has interesting conversations with Uldwyr of Merseia, Aycharaych of Chereion, Peter Jowett of the Web, Tatiana Thane of the University of Virgil, Colonel Mattu Luuksson of the Companions of the Arena and eventually with Ivar Frederiksen.
Like The People Of The Wind, The Day Of Their Return is a rich novel in Anderson's History of Technic Civilization that does not feature any of the series characters of that History.