MTL - The Age of Rebirth: The Little Hot Wife Get Rich From Space - Chapter 41 True Endurance

In the world of Aetheria, there is one name that is feared by all. Yet, he is known more for his title, the Demon General. Whether it’s Gods or Demons, no beings dare to oppose his authority. He ruled Aetheria with an iron hand. Cities are destroyed on his whim. Countries are razed at his displeasure.This is the tale of his rise to power.This is the tale of his rise to Godhood.This is the tale of the rise of the Demon General.

Welcome to Arcadia! The world’s most plausible virtual reality game created by three major conglomerates, Ajin Electrons, Sillicoff Industries, and Argos Corporation. Join Jaeyeong, a legendary gamer who goes by the ID Dex, on a chaotic adventure as he hops in the capsule Dreamer to access the fantasy world of Arcadia! Are you ready?

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.

The ordinary world is not ordinary, ordinary people are not ordinary, and safe places are not safe.

This is a story of a passer-by male protagonist who is entangled by various girls with strange hobbies or even non-human beings while surviving in the cracks and opening a harem.

- Description from novelbuddy