here and can also be found on the companion blog here.)
(I have found confirmation that the Imperial Church in Jerry Pournelle's Second Empire of Man has not only a New Rome and Cardinals but also a Pope. There is a reference to "His Holiness" on p. 69 of King David's Spaceship (London, 1984).)
Poul Anderson writes extremely well, although not exclusively, about war. With some other writers, it is a more central theme. How can space travelers visit a planet where human beings wear armor and fight with swords? Quite easily. In King David's Spaceship -
Interstellar Secession Wars destroyed the Old Empire. In that Empire, Makassar had been a park world with few machines or power installations. The planet was bombarded, then isolated. Its few surviving former service workers were unable to build a sophisticated civilization. Native vegetation is inedible and Earth Stock crops require constant attention.
This determines a social structure:
warriors to protect the cultivators;
military aristocrats unwilling to work in the fields and in any case fully occupied with fighting barbarians and each other;
constant warfare between barbarians, baronies and some cities.
A plausible rationale for continuing to write about warfare.