The Divine Nine-Dragon Cauldron - Chapter 3191 - encountered a huge enemy

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.

I became a side-character who died in anguish because of her good-for-nothing husband.

If I can’t avoid getting married, why don’t I change who I marry instead?

“Excellent, marriage sounds good.”

“Wise choice. Then let’s have a wedding ceremony that isn’t too ceremonious. Following that, I’ll need you to go down to the Fief and behave like the lady of the house until I call for you. Naturally, there won’t be any time to spend in leisure whilst dousing yourself in luxuries.”

“I’m not marrying you, but your father instead.”

“……Pardon?”

“I’m not going to marry you. Do you have a problem with that?”

After dying, Chen Heng finds that he has transmigrated to an alternate reality: everything is the same, except the world is now a Wuxia world heavily influenced by martial arts! Not only this, he discovers that he has a Fantasy Simulator, from which he obtains rewards that make him incredibly powerful in his new reality as well. Martial arts, immortal cultivation, and overpowered abilities–all of this begins from a single simulation!

Can love find a second chance?

Mo Lixin had three medical operations in her previous life.

The first time, she gave birth to his child, but he thought it was some other man’s child. The second time, she had a coronary heart disease, but he never knew. The third time, she needed to replace her liver. but she never breathed again.

She laid down to rest, never to awake.

He remembers her sweet face in particular.

Only when death comes near does one realize a love lost through the seasons of time.

I realize that you are the source of my happiness. I have hurt you… caused you pain… in the next life, I hope to make up for my mistakes… I will guard your happiness… make you laugh… forever… I’m in love with you…

Given a second chance, Ji Nanfeng vowed to never let her suffer. He vowed, forever and always. For her, he’d trod through hell and fire to keep her safe.

- Description from Novelupdates