So I just finished reading "The Foundation and Empire" after reading the first book of Isaac Asimov's foundation trilogy.
It was interesting but to be honest I was a little bit disappointed. The first book was excellent but the second seemed... mundane.
The whole series has a predeterministic theme to it. And while it is a little bit bothersome how the Foundation is saved again and again by the deus ex machina of Seldon's Psychohistory, it is not a show stopper. Not until the Foundation is saved from the Empire by the Emperor's own paranoia.
It is all a bit contrived.
It is worse though... In previous "Seldon Crises", the Foundation faced a problem then solved it. When the Foundation was surrounded by low tech belligerents, he played them off against each other and then used religion to subvert them. When the Foundation faced an aggressor with atomic weapons, the Foundation bought them to their knees through trade embargoes. But when the Foundation got invaded by the Empire, they just did nothing. And the Imperial forces eventually left of their own accord.
Just who does Isaac Asimov think he is trying to kid?
It is ridiculous, what is even more ridiculous is that Asimov could have ended it in a perfectly good way with historically correct justification for it.
By that stage the Foundation was an economic superpower. Historically,economic superpowers don't just lie down in face of a military aggressor. First they try to bribe them (which the foundation did, kudos to you on that one, Asimov) and then after that they use their whopping treasury to spam a military.
One classic case is the various city states of Milan and Venice in the Middle Ages. Most of them didn't have much of a standing army and so would resort to raising vast mercenary armies whenever they got attacked.
I could raise countless more examples.
As history tells us, the economic power may not win all the battles but eventually they win the war, because they can easily replace their losses.
Considering their technological and economic superiority, The Foundation should have been able to raise a death-fleet faster than the Empire could invade their planets, and once a stalemate occurred then the war would become a war of attrition and the Foundation would undoubtedly crush the imperial aggressors.
It would have been perfect to the theme of the story too; that of a budding empire (the Foundation) learning vital lessons on how to grow and maintain control. First there was the importance of religion, then economy and finally the importance of military.
Instead, the Foundation is as weak ever and all because Isaac Asimov is ignorant of the importance of military protection.