Shinji Matou at Your Service - Chapter 503 - : Brahmastra: O’ Brahma, Cover the Earth

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.

Su Yan adored Xie Yu for many years and finally got what she wanted, but Xie Yu ran away on the wedding day, making her a laughing stock. At that time, Bai Xingfan appeared in front of her. He held a black umbrella in his skeletal hand to shield her from the heavy rain, and the other hand stretched out in front of her with a gentle and determined voice: “Don’t be afraid, still With me.” Su Yan was stunned with tears in her eyes for a long time, and finally, she reached out to Bai Xingfan.

- Description from Novelupdates

After a well-lived life on Earth, Kael never expected anything more than death and the sweet embrace of sleep and darkness.But fate had other plans. He was reborn in another world similar to Earth, where he grew up until he was ten, at which point his memories from his past life were reawakened.He was an old man trapped in a boy's body, but the mixture of the child's memories with his own made him feel more middle-aged than old.A few days later, the world he was in ascended into the realm of war, the battleground of all living beings. Kael was among the few awakened who had the chance to become the ultimate god of existence, based on the orbs of different paths presented before him.Kael was faced with three choices:Orb of ChaosOrb of NothingnessOrb of Void(Choosing any will make you undergo a trial that will change your very existence. Please choose wisely.)While in shock by these options and seriously pondering which one to choose, an unexpected event occurred.(Error detected... A new option has been created)(Be the wielder of the three — Chaos, Void, and Nothingness)(Answer picked by host, transporting...)Kael was in shock as he fell into darkness, with one swirling thought in his mind:“I didn't even pick any.”

Hua Jin Lan, a 21st century assassin, was tied up by her sister and thrown into the sea. When her eyes reopened, she had became the daughter, with the same name, of a martial arts family in the Yue dynasty. Some say that the daughter was worthless and just a pretty face; some say she was shameless and proposed to 5 different men a total of 10 times; some say she was a ruthless person and when unable to obtain love she turns to love potions. She was exposed thus while bearing both shame and resentment she jumps into the river and commits suicide……Wait what?