Conquest: Demoted from the Start, I Build the Strongest Empire

I wake up as the ninth prince of Great Qi, with Youzhou as my fief. I only wanted to be a carefree, laid-back prince, But I'm so handsome and powerful that people envy me wherever I go. Luckily, I awaken a summoning System that lets me summon famous officials and generals from history. Fine, I'll stop pretending. Here's the truth: I train troops, repel foreign invaders, build up commerce, grow the economy, encourage farming, and bring prosperity to the people. By the time I've defeated every foreign tribe and conquered all their lands, everyone is stunned. Wait, has that useless Ninth Prince really become this powerful?