I'm a Noble on the Brink of Ruin, So I Might as Well Try Mastering Magic (Manga): Volume 7

Eyeing the promised land's wealth and resources, the human kingdom of Jamille launches an assault! Though Liam wants nothing more than to forget all these politics and just master magic, he now has a whole country behind him and an entire population that looks up to him as their king. It's his duty to step up and play the part. From fighting off an invasion to defending the city-even preparing backups and contingency plans-Liam's got his plate heaped full with nothing but war. Still, his base isn't called the city of magic for nothing; if the leaders of Jamille think it will be easy pickings, they've got another thing coming. The time has come to show the fruits of Liam's magical labors and defend this land that he and his subjects now call home!