That's basically what FE6 and FE8 were about until the story was escalated.
6 is one of the only two I haven't played yet so I don't know about that one, but 8 seemed more like the original with the storyline.
The basic plot of both was: Country gets invaded. Royal child gets help and conquers everyone. Royal child conquers home and wins it back. Royal child with other people go stop main antagonist in their own country.
What I am suggesting is more of everything happening post-war and the actual antagonist is a partially corrupt government, like how the Apostle was against everything but ignorant to what is happening there, but he Senate was controlling everything, so the resistance groups has to win back their country.
Also, it could be where the country you are fighting in was the evil one before the game, like in Radiant Dawn part one as well.
Also, I'm not trying to make it an exact copy of part one, but it is the easiest to make comparisons to.
That is the only other game I haven't played but as far as I know, it is focused more on political (I could be completely wrong but this is what I hear people say). The game would be more focused on the fighting and liberation part, but the antagonist would be more like the government instead of an insane kind trying to rule everything and then kill everyone.
And yes, I am aware that last post was very repetitive at the end.