"Sir Dominic Flandry...sees the rot in the Terran Empire on every hand and knows that the Long Night will inevitably fall upon the galaxy. His consolation is that measures he has taken while fighting to postpone the final collapse may shorten the coming galactic dark age and hasten the rise of a new interstellar civilization."
I quote this blurb because it:
accurately summarizes the series;
curiously parallels Asimov's Foundation Trilogy.
Blurbs simplify or distort, e.g., by using the words "galaxy" and "galactic."
The Allied Planets parallel the Foundation Federation and the later human civilizations in several spiral arms parallel the projected Second Empire envisaged by Asimov's psychohistorians or the unified Galaxy envisaged by his robots but Anderson's imagined societies are more substantial and plausible than Asimov's.
High points in the earlier Technic History were:
"How To Be Ethnic In One Easy Lesson," with its snapshot of everyday life on Earth in the Solar Commonwealth;
Mirkheim, presenting the crisis in the Commonwealth and details of David Falkayn's home planet, Hermes;
"The People of the Wind," mostly set on Falkayn's colony planet, Avalon.