Top Assassin Retires and Becomes a Farmer After Time Traveling to the Past - Chapter 178: Summer insects cannot be spoken of ice

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.

Above the Great Wilderness, there are many sects, and a hundred schools are in full bloom. Not only the three clans of humans, demons and monsters, but also the four unifications of Buddhism, Demons, Taoism and Confucianism.

Ordinary kid Liang Yan, because of a great change in a heavenly bead, embarked on a turbulent fairy path. Since then, he has experienced ups and downs for several times.

Qingshan flute Ren Pingsheng, a fairy in wine with a gourd and sword!

- Description from novelbuddy

Crossing to One Piece world, he became Roger’s younger brother.

Unexpectedly, Gol-D-Roger who was in his fifties had a teenage brother. But he was so weak.

Fortunately, at the age of sixteen, he actually found himself with a possession soul system.

He had attached to the master IP man, also to the White Phoenix and to Ge Nie with his strong ability of the Hundred Step Flying Sword.

If you think that he can only Purchase these? Then you’re wrong!

Pain, Itachi, Ichigo Kurosaki, as long as there is money, any soul can be Purchased.

- Description from Novelupdates

I became a scientist for an evil organization.…But I’m too competent.