Death God of the Drifting Moon - Chapter 71 -

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.

[Ding! The host is about to die socially, the Goddess Conquering System is activated! ][Binding successful! ][Rebirth begins! ]----What Happened wasn't i caught masturbating, how could i rebirth?“System, Introduce Yourself”----[Goddess Conquering System Activated!][Main Strategy Mission Unlocked!][Target – Clara Mackerel][If Clara violently resists or if you experience social death after being intimate with her, it will be deemed a failure, and you will restart.][Upon completing the mission, system rewards will be given]----“System, do you have any other functions? Is there a beginner's gift package?” Harry asked expectantly.[This system only issues Goddess Conquering missions and rewards for completing those missions.][In the event of failure, the system will select a time period for the host to rebirth.][Other functions must be discovered by the host.]

Arakawa Kouki is reincarnated to a Japan with a different history than the Japan he knows with the memories of his previous life still intact. Kouki was discouraged, “Aren’t reincarnation stories supposed to be at some fantasy world filled with swords, magic and elves?!”

“A qualified gunner should have enough firepower coverage.”

“So my battery has a diameter of three thousand meters, which is very reasonable.”

After a grand fireworks, Chen Jiang looked at the shocked eyes of the passers-by around him and said seriously.

…

When all races were thrown into a world and started to fight, a world with the theme of survival began.

- Description from novelbuddy