Breaking Free: Love & Rebellion at Blackthorn Academy. - Chapter 71: SWIMMING SELECTION.

5 years after the world changed, the final boss appeared.

Is he a genius in the spotlight, or is he a madman behind the scenes of the Second Avenue?—-After getting the final relief from his past sufferings, Chu Jiashu was given a second chance when he found himself in the body of an infant from an aristocratic family of Hall. Now, nothing is going to stop him from achieving his long-cherished dream of acting. Enter Renly Hall, a Hollywood miracle of 21st century.

Xie Jin is an international student studying in the United States. Because of an accident, he obtained a special ability that allows him to detect the attributes of all objects within a certain range. Because of this ability, he started from panning for gold and gradually went to the country of Bald Eagle. The pinnacle of wealth. (No abuse, no depression, logical, straightforward and reasonable road to the rise of North American chaebols)

- Description from novelbuddy

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.