Alchemy Emperor of the Divine Dao - Chapter 1: Rebirth

One will to create oceans. One will to summon the mulberry fields.

It always starts with an accident.That’s how all these stories go. One moment, you’re minding your own business, and the next, you wake up in someone else’s body. For Caspian, his accident started earlier than he even knew.Maybe it began when his sister got him into romance novels? Or when he started really sympathizing with the villains at the ends of books? He’d never know. It was too late to worry about it now.For now, he had to find a way to fix this nightmare, or rehabilitate his image, all while trying to free himself from the fate set out for him. All because of the damn “gods” who he'd cut a deal with.These were the only two options he had available, and he wasn’t sure he could succeed at either. The man he had taken over for had been…a true piece of work. And the secret villain of the book he had been reading before he passed.It had been a harem novel. A reverse harem novel.He was trapped in a huge ass CASTLE with a bunch of men who hated him because he was taking affection and time away from their shared wife. All Cass wanted to do was be a good person, not mess around with this poor woman and her far too handsome husbands.But why would no one leave him alone? Was he too suspicious? And why, after going out of his way to avoid them like they had asked, did they keep pestering him?And where did the heroine go?How was he going to manage three, handsome men without the heroine?

Sean: Hello, I look up to you like a torrent of river water, uh, can I shake your hand?

One day, he shook hands with Sean suspiciously.

Sean turned around and laughed wildly in his heart: Hehe, the top knight talent is in hand.

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- 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.