Harry Potter: Returning from Hogwarts Legacy - Chapter 8: Magic Wand and Birthday Present

An ordinary student accidentally traveled into an other universe and became the king of a small kingdom. He had gotten a “Cheating Code” of life and was able to complete something extraordinary. This is the story about a king that was able to conquer continents and leave behind him an ultimate legend that will be recited between every generation to come.

- Description from novelupdates

In a world where mysticism and steam industry coexist, cursed objects, the Reception Bureau, and Evil God fanatics...That year, the King was bedridden with illness, the successor was inexperienced, and power slipped away, leaving the empire teetering.That year, external forces gathered around the empire, and foreign civilizations eyed it covetously.That year, the prophet delivered a prophecy that the era of civilization was nearing its end.That year, Ethan arrived at a small town on the outskirts of the imperial capital. To survive in this perilous era, he began practicing Fireball Skill.Years later, Ethan looked at the meteor falling from the clouds and realized there was a problem.The beginner Magic he learned seemed a bit off.

I was once asked a question.“How far would you go for her?”“How much are you willing to suffer just for her ?”“Would you sacrifice yourself for her?”I answered“I will sacrifice myself, but at the same time I won't ”Why? He asked“It's simple ” I replied“I'm willing to die 9999 times just for her but on the 10 thousands time I won't die I'll live with her and make her happy ”“Why not a billion times”“It's simple it's because I love her and she loves me, I will live with her after 9999 deaths she needs me and I need her that's how much I love her”“Then die, die 9999 times just for her and save her from this world”“I intend to ”

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.