One Piece: God of Space - Chapter 257 A different sun

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.

Bathed in the love of her imperial family and her husband, Yun Shang was a spoiled princess and the envy of many at the Royal Court. Her life had been perfect right up till the moment when she realized that everything was just a sham, a ruse designed by the Empress to ruin Yun Shang. After enduring bitter treachery and being poisoned, Yun Shang died with a broken heart and an unfulfilled vow of vengeance. As if God was answering her final request, Yun Shang found herself reborn like an immortal phoenix. She was eight again, and all her memories from her previous life remained intact. The others, however, did not remember the events leading up to her death. Determined not to repeat her mistakes, Yun Shang planned to rain hellfire onto the treacherous, backstabbing villains for all the heart-wrenching pain they had once inflicted upon her. He was the handsome and smart prince of the Ning, who was revered as a battle-hardened general that knew no match in the world. He had thought he wouldn’t settle for anyone until she showed up. A seemingly innocent young princess and a gorgeous prince. Where would their relationship lead them?

- Description from Novelupdates

Wen Xuxu is a tenacious, talented, smart and brave woman who was fostered by the Yan family at the age of four when she lost both her parents.

Brought up to be the successor of a huge conglomerate, Yan Rusheng is an aloof, intelligent and arrogant man who is the most sought-after bachelor in the capital city.

Despite growing up together, both of them seem to treat each other as an eyesore. She labels him as a jerk and womanizer while in his eyes, she is a shrew.

Over time, they fall for each other, but they continue to conceal their feelings for each other. By a twist of fate, they are forced into a marriage. And unknown to everyone else and Yan Rusheng, she has harbored a deep secret for many years…

- Description from Novelupdates

Young Master He had always been a male god in the eyes of others.

Until one day, the god-like him died.

And he became the much detested white silk trouser-wearing second rich generation.

Male God He was unaffected by this.

In his previous life, he had sacrificed everything for his clan, now, he could finally break free from that tiring life.

The only thing was that he had gained a handicapped partner.

Initially, he thought his partner was just a weak, gullible and pure lamb.

In the end, a certain person changed entirely making everybody cry and shout daddy.

- Description from Novelupdates