Trouble - Manga
Summary
The God who rules over the vast world of ‘Rodowan’ one day announces a new Divine Law. All reproduction is immediately prohibited. Those who are banned from conceiving rebel for the sake of humankind and their children, but the power of God and their followers is overwhelming and oppressive. God brands children born after the Divine Law as children of traitors, killing them or turning them into slaves. In this chaotic world, those who wish to punish this sick tyranny begin their desperate fight.
... and the second season of the Anime did a better job of pacing than I thought they would. I think they moved the Elf village arc from before hostilities with the Principality began to the inter-war period, aka the start of the second season, and used that to pad it out. Good call if that's what they did. In any event. Good season.