Tsuki ga Michibiku Isekai Douchuu - Chapter 414: Leviathan Levi

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.

In 2028, the Abyss invaded, accompanied by the arrival of Extraordinary Power, bringing Blue Star into the era of universal awakening.Chu Xiu, a transmigrator who inherits the Infinite Saint Dao Sect, looks at the insane Demonic Secret Techniques before him and falls into contemplation.“Crafting a Bone Banner requires the sacrifice of hundreds of mortals. Well... do zombies count as humans?”And he quickly discovers that those Abyss creatures work exceptionally well for crafting Demonic Artifacts. Most importantly, their number was almost inexhaustible!

I got hit by a truck and woke up in a world unfamiliar to me.[System rebooting… AI core active.][What can I help you with?]With a hologram screen floating before me, Chat GTP, the pinnacle of artificial intelligence.[Combat mode activated.][Here is the steps to create a atomic bomb.][Efficiency: 99.8%. Shall we proceed with conquest?]And with it, I became the most dangerous man in this world.

Time flies quickly; may you enjoy a cup of drink.I know not the height of the green mountain, nor the depth of the earth.Only watching as the seasons change, that it took people's lives.