Friedrich no Senjou: Shinku no Tensai Gunshi, Uso kara Hajimeru Eiyuutan

Friedrich, a former orphan and brilliant young man, has lived a quiet and peaceful life in a rural village. However, that peace is abruptly shattered by a raid from a band of thieves. While the villagers are consumed by despair, Friedrich is different—he stands before the people and proclaims: "I am the son of the hero. If we follow my plan, we will surely win!" This is the story of a young man who was once a nobody and becomes a great hero whose name will be etched into history.

(Source: Overlap, translated)