One Piece – Thundergod Marine - Chapter 92 Disturbance Part 2

The summer of 2006 was very hot. Chen Yang, who had just graduated, decided to borrow a sum of money first to make his future different.

- Description from novelbuddy

What if Magic has always existed ever since the beginning of the Earth we are living on, but history has been written in order to hide these facts. What if the prosperous and well-known people in history is actually a mage?

Enter a magic academy, rule your country. Be at the pinnacle of life! Join me in the journey of Emery and the others in the world of Knights and Magic as he becomes the Earth's Greatest Magus.

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.

His name was 25. On Avalis, he was just one of many tasked with fulfilling missions for Earth’s people. This time, he was given a simple one—live as Zeno Han and have an ordinary life.Easy. Or so he thought.The moment he took over Zeno’s body, someone shoved a script into his hands. “You’ll be perfect for this role!” And just like that, he was on set.[Fame Meter: Unable to Measure. Off the charts.]Doctor? Check. Pilot? Check. Eunuch? …Regrettably, check. Every script forces him to relive past missions, and somehow, he’s nailing every performance. Now, the industry wants to make him a star, but can he still complete his mission? Or will fame—and the terrifying unknown of failure—be his final curtain call?