Skill Hunter -Kill Monsters, Acquire Skills, Ascend to the Highest Rank! - Chapter 268:. Equilibrium

At eighteen, her mother died in a car accident, leaving her all alone in the world. One day, her kindness in rescuing someone led to a life-changing transformation.She was provided with food and accommodation, and someone even arranged for “360-degree personal protection” for her!Just when she thought she had picked up a pie from the sky, she was tied up and sent to a training camp, embarking on a tough yet passionate new journey.Bully her? With Taekwondo, she'll beat you until you can't tell north from south!Compete with her in sniping? Rookies, step aside, she's challenging the strongest sniper!Doubt her hacking skills? Come on, sister will show you what playing with computers is all about!She stood out in the camp with high profile, top in every category, who would dare compete against her?Back home, the little overlord turned into a docile rabbit, utterly bewitching someone!Unable to endure it any longer, he dragged the little overlord to the civil affairs office and registered their marriage.At night, he returned home, and righteously set about 'educating' her!

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.

Her original self was a powerful jiangshi who had cultivated for innumerable years. However, when she attempted to unlawfully enter the world of the immortals, she was discovered by the Jade Emperor and thrown into the mortal world as punishment. Her soul then left her corpse, fusing with the body of the Motian Dynasty’s sixth princess. She didn’t even have a chance to fully comprehend her current circumstances before her maid unexpectedly ignored her mistress, even publicly provoking her!

“What? That weak and cowardly idiot who has neither her father’s love or mother’s favor actually mistook her older sister as her maid?! All the royal princes in the world loathe her?”

“Damn you! This old lady will let all of you understand why the flowers are so red!”

“Hey! Did you hear? That cowardly sixth princess unexpectedly snatched away the man that the eldest princess favored today!”

“How is that interesting news? That fourth princess who ran always ran amuck in the capital city is now confined to her bed now!”

The good-for-nothing counterattacks! The previously cowardly and incompetent sixth princess suddenly reveals her exceptional talents! She is full of radiant elegance, and unparalleled disdain!

She is driven by the desire to shed no more tears! However, if she had known what would happen later, she would have been better off acting stupid! She had calculated thousands, tens of thousands of scenarios, but had never calculated one where one day, her own prey would unexpectedly turn around, and ruthlessly bully her instead! Damn it, she still hasn’t sucked any blood yet!

- Description from Novelupdates

The next morning, Jian Anning asked, “What is happiness?” Yu Xingxing hooked his lips into a smile and suddenly pulled her into a tight embrace. “Happiness,” he said, “is being with the one you love and doing things that make you happy. Let's continue, wife!” Jian Anning kicked him off. “Get lost!”