Others Level Up, but I Pursue Cultivation! - Chapter 1460 - 514: One Hundred Thousand Years of Sword Training, Sword One Mahayana! (Part 3)

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.

Having reincarnated into a different world, Murong Lin found himself utterly bewildered.The golden finger system informed him that he needed to eliminate the protagonist—wait, he wasn’t the protagonist?Innocently, Murong Lin turned his gaze towards the designated heroes, a butcher’s knife clutched in his hand. Regretfully, he realized he had no alternative but to end their lives if he wished to survive.Hold on, this pig was a protagonist too? And that tree?Without any choice, Murong Lin found himself forced down the path of bloodshed.

Three thousand years ago, gods and Buddhas disappeared all over the sky, and the inheritance of practice was broken. It was not until the ancient civilization was destroyed that spiritual energy recovered. Ten thousand races took advantage of this to invade.

Five hundred years later, the human race gradually rose up and began to fight for control of the land of China, and counterattacked all races.

Three hundred years later, Fang Yi, the Lord of the Great Dao, slaughtered all clans, destroyed all the heavens, stepped out of the myriad realms, and fought against the Dao of Heaven.

In desperation, Fang Yi sacrificed blood to eight hundred small worlds, reversed time and space, and was reborn nineteen years old.

In this life, he wants to live a more relaxed life, perfect his Dao Xin, and conquer the Dao of Heaven again.

- Description from novelbuddy

After death, Gu Jin realized the child, whom she had fed only once in the past, was the only person who gave her proper burial and avenged her by any means. Once she’s reborn, she found him when he was being bullied. And despite objections, Gu Jin took this malnourished child under her care with help from the dimension in her possession. However, never did she expect she would lead him astray...Many years later, Gu Jin can’t help gritting her teeth as she is watching the elegant and handsome man on TV. He has grown up to be a successful and powerful businessman who is outwardly kind but inwardly ruthless. Most unexpectedly, he has turned into a man who is domineering and protective of her.