There are two ways to begin a narrative.
(i) The text can plunge in media res, into the midst of things, with the viewpoint character's perception of a particular scene or even with a burst of action: two of Poul Anderson's heroes are introduced to the reader as they dive into water to escape from an immediate physical threat.
(ii) The narrator can contemplate the events to be described and place them in some historical, or at least wider, context before introducing the - or at least a - viewpoint character.
Anderson's History of Technic Civilization concludes with four works set in the post-Imperial period. Working our way back from the end of the concluding volume of Baen Books' The Technic Civilization Saga, we find the following three beginnings:
"'From another universe. Where space is a shining cloud...'"
-Poul Anderson, Flandry's Legacy (New York, 2012), p. 711.
(The viewpoint character is listening to a recording.)
""Moru understood about guns." (p. 663)
(Moru seems to be our viewpoint character, although he is soon succeeded in this by Evalyth.)
"The Quetzal did not leave orbit and swing toward the planet until she had got an all-clear from the boat which had gone ahead to make arrangements." (p. 545)
(Thus, immediate action, with a viewpoint character introduced and named two sentences later.)
These are three in media res beginnings. By contrast, the first post-Imperial work, "A Tragedy of Errors," begins with a short italicized paragraph separated from the text of the story by three blank lines. The italicized passage begins:
"Once in ancient times, the then King of England told Sir Christopher Wren, whose name is yet remembered..." (p. 457)
Thus, this text begins with a historical reference. Further, reading the story immediately after the previous installment of the Technic History, we know that the word "...yet..." refers to some period in our future, either in Dominic Flandry's time or, as we soon realize, later.
The story itself begins:
"Later ages wove a myth about Roan Tom." (ibid.)
Thus, Tom will be the central character. However, the narrator is either omniscient, entirely detached from the narrative, or is an inhabitant of a much later age, able to look back at the intermediate ages in which there were myths about Roan Tom.
So far, in the Technic History:
Hloch of the Stormgate Choth on Avalon has presented an Ythrian perspective on human history from the Grand Survey to the early Terran Empire;
other commentators, Le Matelot, Vance Hall, Noah Arkwright and Urwain the Wide-Faring, have presented their perspectives on the period of the Polesotechnic League;
Donvar Ayeghen, President of the Galactic Archaeological Society, has commented on the founding of the Terran Empire;
an unidentified narrator has addressed readers of the History thus:
"Consider Helen Kittredge. We pick her name at random out of personnel data. These say little more about her than that..." (p. 276)
Thus, this narrator, living at some period of the History and having access to Naval data, admits to his ignorance (lack of omniscience) and goes on to speculate about the course of the Magnusson Rebellion as experienced by the randomly chosen Helen Kittredge.
Now another, or possibly the same, narrator comments on the myth about Roan Tom.