Shokei sareta Saikyou no Gunyou Majutsushi, Haisenkoku no Elf Hime to Kokka Saiken su: Sokoku yo Jama suru no wa Katte da ga, Sono Majutsu Tsukutta no Ore nanode Kikanai ga?

The magical nation of Ingressa came to dominate neighboring countries with the power of groundbreaking military magic. Supporting this dominance from behind the scenes was Hert Eisenheim, who rose to the rank of archmage at a young age. However, due to a scheme by the court magician who was jealous of his talent, Hert was executed as a war criminal–-but when he awoke, he found himself summoned before a young girl. The girl's name was Iris Refrain, and she was the first princess of the elven kingdom that he had destroyed. This is the start of a rebellion fantasy story about a banished man and a girl rebuilding her destroyed nation!

(Source: Flex Comix, translated)