Regression of the Third Prince

Story

Between looming war, fighting nobles, and an overbearing father, Prince Yuri Briol has a lot on his shoulders. He's also carrying knowledge of his past life while trying to change the course of history. This cast of characters includes a famed assassin, a powerful mage, a loyal maid, and a lazy knight among the character-filled kingdom of Briol. Yuri may be the third-born prince, but he could also be the most important factor in his family and kingdom's survival.

Synopsis via AniList (English).