After Being Sold Out By The Empire, I Decide To Assist The Demon King - Chapter 23 - 22: A Smile That Leaves You at a Loss Whether to Laugh or Cry

It’s said that the prince of virtue had almighty martial arts. It’s said that the prince of virtue had the most handsome appearance in the world. It’s said that the prince of virtue was brilliant. But all was legend! A fire ruined his wonderful appearance and his legs. Even the talented bride under their marriage agreement were replaced furtively. Ye Liu-li was his bad-luck substitutive princess. She went a long way to graduate from Medical University and had her internship with pain and joy. Who knew that in order to save a suicide patient, she fell off the building and crossed time into a “chessman” of prime minister. She had also been married to the disabled prince replacing her elder sister. On the wedding night, when most other couples were having their romantic night, she was thrilled. It didn’t matter. Revenge never came too late. She would never let go of any of them who entrapped her or harmed her.

- Description from Novelupdates

A generation's mighty and most powerful expert died mysteriously and reincarnated without any memories on a small planet far away from the Cultivation World.

This small planet was earth.

Five thousand years ago, a great calamity descended on earth. Countless Spatial Cracks appeared in the sky and beasts invaded. After hundreds of years of fighting, humans discovered they could awaken a battle spirit that can help them raise their strength and grant them the abilities that were simply unimaginable for humans before.

Qin Feng also awakens his battle spirit but unfortunately, it was swallowed by his own birthmark, The Infinity Symbol.

This was just the beginning of the mysteries that surrounded him like invisible specks of dust. He soon discovered that the 'Infinity Symbol' was actually not his birthmark but something mysterious from another world.

The Infinity Symbol helped him awaken a Divine Battle Spirit and granted him a Nameless Cultivation Technique that was beyond the world's limit.

He also discovered that he could not die! Every time, he was killed, he returned back in time with the memories of what is going to happen in the future.

Soon after awakening the Divine Battle Spirit, a mysterious beautiful lady stepped into his life and told him that he does not belong to the earth. He was actually the reincarnation of someone called 'KING'.

The mysteries that surrounded him like the invisible specks of dust started to come on the surface from the day of his awakening, revealing many secrets to him.

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.