...So how the hell did things get to this? Well, let's step back and consider how things got this far...
We start with the assembly of the Apostle's Army. Begnion marched into Crimea without so much as considering them a separate nation, and while Elincia did an excellent job at asserting Crimean independence, this wound up causing a massive chain reaction that, combined with the sudden and perfect timing of the apostle's arrival, firmly divided Begnion and dissolved the Central Army headed our way. Crimea, Gallia, Phoenicis, Apostle's Begnion and the Greil Mercenaries could unite at last with a common goal and hope to see it fulfilled.
And then we plunged into the war with Daein. Who got help from Goldoa and Hatary. And Kilvas was there. Nearly everyone important on this continent had some role to play on how the battle at Nox occurred. And however the definition of "world at war" is defined, I think it can safely be said that 3-E qualifies as such. It's a pretty good comparison to Gronder Field, in that respect- it's a massive pile of casualties that causes more problems than it solves, even if it mechanically plays out like a good setpiece.
There's one thing that can't go without mention when talking about this part of the story. The Blood Pact. Lekain's twisted bioweapon that can twist Daein's arm into doing whatever he wills. Without this Pact, the story does not proceed in the same direction. It's easy to blame the Pact itself, but honestly, I think the Pact does what it needs to do. It shows Pelleas as a weak king that should never have been given power, shooting the gun that Part 1 mounted on the wall. It establishes Lekain as a conniving bastard worthy of his ultimate fate, as opposed to Valtome and Numida, who earned it through their own actions- it's important to keep in mind that while the Senate is full of assholes, Lekain is the biggest of the bunch. And it ties in to the other Blood Pacts running around- such as Ashnard's murderous cut in line to the Daein throne (which would have been much more obvious if one couldn't blame a plague).
That's not to say the plot point is flawless, however. But it's not the Blood Pact's fault. The problem is that Daein was not given any reason to oppose the Apostle's Army. With Micaiah, a Branded who actively stamps out laguz persecution, at the helm, the Daein Army wasn't allowed to chase the laguz for bounties as openly as one might've liked: Begnion offering to pay Daein large sums of money for laguz heads is as good a reason as any for 3-7 to happen. And when the beorc get involved, and even the Empire is in open rebellion against the very people who caused them so much misery? Why wouldn't Daein take their side? Ultimately, the biggest problem here is that the faction that caused Part 1 is the same faction the Apostle is fighting in Part 3. If one wanted to get an actual ideological conflict in Part 3, the likes of which Fates and Three Houses would later get a grasp of and actually play for what it was worth, the best thing to do would, ironically, be to have Crimea be the occupying faction of Part 1. ...Although perhaps that would've made Part 2 too hard to jump to for new players. As it is, Micaiah is not fighting for anything, no matter what localisation inclusions were added to bridge the gap and make Micaiah more laser-focused on "protect this racist country that would lynch me as soon as they found out who I am".
I often call Tellius the most politically minded FE story before Three Houses. I stand by that statement- Fire Emblem usually cares much less about politics than this game does. But it is clear as day that Tellius was very much the first stepping stone that Fire Emblem had to take before games like Fates and Three Houses could exist, where the ideological conflict between two factions was actually a conflict. On the other hand, one advantage those two games have over Tellius is that Tellius is required to end the game with everyone on the same side. Although one could, somewhat, make Daein a proper enemy for the Apostle's Army with some plot tweaks here and there, each tweak would have to be undone to put Daein back together with everyone else for Part 4. I think the problems were a little more... fundamental.
