The War Of Two Worlds

The text of Poul Anderson's The War Of Two Worlds (New York, 1959) comprises:

an introductory passage without a heading;
Chapters I-XI;
an Epilogue.

In the unentitled introductory passage, "...Intelligence Prime, lord of the Solar System..." (p. 5), described as possessing  a "...great crested head..." (p. 6), starts to read a text hand-written by a now dead Earthman called David Arnfeld.

It is a safe bet that Chapters I-XI are narrated by Arnfeld and that the Epilogue returns to Intelligence Prime's pov.

Prime's people have conquered Earth and Mars. He refers to "...the Exodus..." (p. 6) and aspires to "...know peace under friendly stars..." (p. 5) so the conquerors seem to have crossed an interstellar distance. Although he is "lord," he operates in secret:

"It was not risky for him to appear at the window. His secret office was so high above darkened Sao Paulo..." (p. 5)

Contradiction?

Arnfeld's text, dated 2043, gives his birth year as 2017, just four years from now and five years before the start of a war. He entered Lunar Academy at the age of twelve and was exec of Pallas Base at twenty five so his twenty first century has more interplanetary capacity than ours has had so far.