Kiss Goodnight, Mr.Ji - 1821 Are you together with ah Luo?

She was dressed in white, with a mysterious orchid imprint on her forehead, her skin like jade is always covered with a veil. Since childhood, she had left her parents due to her special status and lived her life with her master in the clouds. She was not yet ten when her medicinal skills were renowned in the world. In order to save the people, she descended the mountains, however, she encountered a storm on the way to the epidemic area. The man who saved her would tease her for enjoyment, little did they know…

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.

This novel is also known as Phoenix Cry Firmament

The previous owner of Mu Ru Yue’s body had been poisoned. Because of this, her meridians were blocked, hindering her cultivation, which eventually led to her being known as trash. After being beaten to death, Mu Ru Yue, who had originally been a successor to a medicinal aristocratic family in Hua Xia, reincarnated into her new body.

They want to seal my path?

I will train to reach the peak of the realms!

They give me a foolish prince as my husband?

I can make do with him.

It would be easier for me to deal with him, rather than with other candidates who would be thrown at me in the future. I shall strive to become powerful enough that nobody will be able to mock or kill me!

- Description from novelupdates