Elysium's Multiverse - Chapter 326

As he transmigrates across the continent of Douqi, Gu He takes on the mantle of Alchemy King Gu He and gains an incredible power - the Ten Thousandfold disciple cashback system. This allows him to grant gifts to his disciples, which are then returned ten thousandfold.“You have gifted Liu Ling the Green Lotus Core Flame, triggering a tenfold return and granting you the mighty Green Lotus Holy Fire!” the system announces as each gift brings Gu He greater power.After three years of intense training, Xiao Yan returns proudly to the Yunlan Sect, eager to display his newfound strength.“Don't underestimate this once poor youth!” he warns his former lover Nalan Yanran. “Today I'll show you what a true genius can do!”But Nalan Yanran just smiles faintly. “Is that so?” she asks, as a terrifying Dou Emperor aura suddenly surges from her.Shocked, Xiao Yan stammers in disbelief, “How did you become a Dou Emperor powerhouse?”With an arrogant smile, Nalan Yanran replies, “With my master, anything is possible.”

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.

He became the Emperor when he was just a boy and was beheaded before reaching adulthood. It was a tragedy brought about by his fate as the first noble wizard.“Ian, don’t be born in your next life.”He thought everything was over, listening to the traitor’s heartless words. He knew, but…“You are a symbol of peace. Where else would you find such honor as a lowly one?”He became the Margrave’s bastard son, whose family went extinct 100 years ago.A lowly, unsophisticated one, destined to be sold as a hostage to the barbarians across the border.

In the Tranquil Sun province of the empire, there exists an unremarkable lordship known as Xue Ying Territory! This is the home of the Dong Bo clan, the clan of our hero Xue Ying!

His father, a commoner turned noble; his mother, a noble who abandoned her clan for love, and his brother, an innocent toddler. But peace cannot last forever, Xue Ying’s peaceful life is shattered, and the only way to reclaim it is through power!

- Description from novelupdates