MTL - As a Captain, You Must Be Cold - Chapter 1

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.

Leon Thorne was the disgrace of his house, overweight, softspoken, and dismissed as a failure before he ever picked up a sword. Mocked during the Awakening and branded an F-rank, he was expected to fade quietly from the halls of power.But he didn’t.Because this wasn’t his first life.In another timeline, Leon watched House Thorne fall, shamed, scattered and erased from history. Powerless to stop it then, he’s been given one chance to rewrite it now.Stripped of excuses and reshaped by hardship, Leon claws his way forward—through blood, sweat and silence. Now, leaner and sharper, he enters an academy where only strength speaks and legacy decides your worth.But Leon carries no crest. No backing. Just scars, a sword, and the will to shatter fate itself.He’s not looking to be acknowledged or praised.He’s going to rewrite everything.NO MATTER WHAT IT TAKES.

Violence, Rogue, two names that had long since faded away from the limelight. In a new game, The Strange World, they appear once again. The two former legends, once more rise to glory.

- Description from Novelupdates

One of the few self-cultivator who exist in this modern world; due to an unfortunate event, completely destroyed his body in an explosion. Using all his effort to save his primordial spirit, he ended up in an strange magical world and had to start all over again. From a fallen aristocrat to the Warlord of Chaos, this can no longer be summarise as legendary; this is the life of the God of War.

- Description from Novelupdates