The Emperor Abdicates from the Start, While a Hundred Thousand Barbarians Surround Dragon City

Reborn and transmigrated into ancient times, I became the least-favored prince of the reigning emperor.

Then the northern barbarians surrounded the capital with their cavalry. The old emperor fled with his other sons and daughters, passed the throne to me, and left me alone to clean up the mess...

Damn it!

Master physics and chemistry, and you can go anywhere without fear. A mere cavalry force from the northern barbarians? Watch me mow them down with machine guns and cannons...

What? Now that I've driven back the northern barbarians, the old emperor wants me to give the throne back to him?

Not a chance!