Starting as a Son-in-law to Establish an immortal Family - Chapter 980 - 350 Men are inherently tough but gentle as

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 a shocking turn of fate, Jack Anderson's life is brutally cut short. But death isn't the end for Jack; instead, it marks the beginning of an extraordinary journey.Reincarnated in a mystical realm, Jack discovers he's been gifted with incredible powers and an enigmatic system that guides his every move. As he navigates this unfamiliar world, Jack must confront formidable enemies, unravel ancient mysteries, and unravel the secrets of his own destiny.With the undead system as his trusted ally, Jack embarks on a perilous quest to unravel the truth about his past, his newfound abilities, and the hidden forces manipulating this strange new world.Will Jack master the undead system and unlock its full potential, or will the shadows of his own mortality consume him? Dive into the world of 'The Undead System' to join Jack on his heart-pumping, action-packed adventure through the realms of the unknown.

A striking man of mysterious origin and peerless talent, he looks back at the world, in all its entirety, with utter disdain. And yet, in the treacherous and unpredictable ultimate formation of the Boundless Secular World, he guards a breathtaking ancient qin with broken strings, waiting silently for the destined one to arrive!

A boy encounters him, and knows for the first time that the world beneath the Heavens is a fickle place. Not even demons, devils, ghosts and monsters can match the frivolity of human nature!

A slender physique, and jade-like beauty, but the sword that strikes between heaven and earth is not unlike a streaming rainbow!

The vastness of the starry sky, the seven emotions and six desires! Greed, anger and ignorance! The teachings of Buddha will grant you boundless strength!

A sea of blood will come, at the cost of all mortal beings full of honest hope!

The ghosts wail as the gods roar, but the sea of blood has no end!

Where, pray tell, is the path I should take?

Since there is no path, no matter how bitter and bloody the sea, even if my boat is made out of bones, I will soar to the heavens above!

- Description from Novelupdates

However, he did not know that he was not raising just a harmless pet, but a biological weapon secretly made by the government… a real monster.

As a former librarian, Rand felt that he had been living an ordinary life, the one that he had reclaimed unconsciously every single day.

Recently, he has been a little upset because the pet fish he accidently brought home to raised seems to have undergo some strange changes

Well, it turned into a merman.

- Description from Novelupdates