Flash Marriage: The Domineering Wife - Chapter 396 The Plan

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.

Ethan Walker a normal boy was just playing his game favorite game [Legacy Of Heroes]. But who would've thought fate had a different plan for him.“Why him of all people!?”Transmigrated into the world of the game he takes on the role of Noah Von Blitzfeld, the younger son of the Blitzfeld Duchy, who was fated to die while saving his fiancee in a disaster unfolding in the academy.

The servant looked at the grieving princess. “Your Highness, the Regent Prince sent your scholar fiancé to the Western Butcher’s daughter!” 

The princess gritted her teeth, speaking to her servant that it matters not as she has other suitors in line. Many days later, much to her dismay, the servant ran in a hurry. “Your Highness, the Regent Prince expressed his intention of becoming your suitor! All other men in line were sold to Gou Lan Red District!”

The princess was distressed. She said to her servant it matters not. She’ll soon be married to Prince Fuma. Then the uneventful came. The servant once more ran to her, almost tripping in the process. “Your Highness, Prince Fuma was imprisoned at home! Meanwhile, there’s a red sedan chair waiting at your residence for your marriage! It was led by the Regent Prince!

The princess was stunned. For a day such as this to come, it seemed impossible. This nothing but a sad story of a female boss crossing back in time to hold the thick thighs of the big boss. But while raising him, she was eaten in the process.

- Description from Novelupdates

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