Marriage contract: Genius baby's belly daddy - Chapter 2469

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.

Just like how everyone adored heroes in their childhood, a certain young man adored those powers hidden in shadows. After hiding his strength and living the mediocre life of a mob character by day while undergoing frenzied training by night, he finally reincarnates into a different world and gains ultimate power. The young man who is only playing at being a power in the shadows, his misunderstanding subordinates, and a giant organization in the shadows that gets trampled…. This is the story of a young boy who had adored powers in shadows possibly eventually reigning over the world of shadows in another world.

After everything that Zaroth had was stolen from him, he decided to live solely for his desires, morals be damned!Close to his death, he resurrects and tames a mythical dragon, who turns out to be a breathtaking woman.Learning that in order to explore her body, he must grow stronger so he doesn’t die during the act, Zaroth sets a clear goal for himself: to get stronger.“But I’m curious about something.”“Hm? What is it?” Luna asked, raising an eyebrow.“You said you judged me. How did you do that? Why was I worthy?”Luna’s smile darkened, her eyes glowing with a dangerous intensity.“Despite knowing you would die, you didn’t pray to the gods. On the contrary, you declared that you would kill every single one of them like the dogs they are. In my life, you’re the only one who’s ever made such a declaration, which is why I couldn’t leave you behind—someone who dares to share my dream.”

It is an era of artificial superintelligences, interstellar travel, gene medicine, and virtual reality worlds. Far into Earth’s future, 15-year-old Gu Ding is a student of Cerulean Military Academy by day, and tavern waiter by night. His ambition: Become the space pirate with the highest bounty offered by the Universal Federation Government. With the help of Neptune, a neonate super-intelligence, Gu Ding finds himself thrust into a galaxy of shadowy organizations, political underdealings, and otherworldly forces that lie beyond human comprehension…