Final Boss - Chapter 165: The Eve of Joyce Fortress’s Siege War (Part 1)

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 oldest myth between heaven and earth reappears in the world, countless spaces begin to slowly interweave, and the dark side of the world quietly emerges.

Advocate the friars who are weak in flesh and blood and eternal in spirit. Showing a tyrannical body, there is my invincible martial artist.

Looking at the changes in the world, Lu Ren exhaled in a panic.

“Ding, because of your uninterrupted breathing for 26 years, you suddenly realized something, and successfully realized the breathing technique.”

Hearing the prompt sound in his mind, Lu Ren waved his sword hesitantly.

“Ding, because you were blindly poking a few times with your sword, you suddenly realized something and successfully learned basic swordsmanship.”

After a long time, he looked at the army invading from another world, raised his long sword and slashed it out.

In an instant, the endless air waves rolled back, and the mountains and rivers where they passed collapsed, and the rivers fell.

Then the army was annihilated and bombarded towards the different world. The entire other world was completely shattered by the explosion of infinite fire, and slowly disappeared into the air.

- Description from novelbuddy

It was an enormous tsunami that completely covered the sky, and due to its dark water, the sun had been blocked out. A sense of despair ran through everybody as they looked towards the peaked wave quickly crashing down. But was I the only one who noticed the massive sea monster lurking towards the front of the wave? CRASH [Requirments Met] [System has been chosen] [Your god has been selected] [System Granted] [Poseidon System is being installed]