MTL - SCP Life Diary of a D-class Personnel - Chapter 120 : Skilled use of Death Flag...

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.

A new work from the author of 'My Senior Brother is Too Steady', welcome to enjoy it!-------[Science Fiction Apocalypse Setting + Alone Cultivation Protagonist, Not a Mindless Feel-Good Story]This is a shattered world where human civilization barely gasps for air on a planet ravaged by the Blade Beast catastrophe, the flame of civilization in underground fortresses flickers intermittently, and human elites in space are brewing a final plan to strike back at the Blade Beasts, but the future of humanity is dimly lit by fading stars…“So,”a Mahayana Realm expert, who after cultivating alone for one hundred and twenty-five years failed his tribulation and became a Residual Soul in this 'peculiar' world, sighed deeply as he looked up to the sky:“What the hell does this have to do with me?!”

As tragedy befalls Xin Siyue, she soon finds herself transmigrated into a novel world as a character. To her disappointment, she became the villainess who obsessively chased after the male protagonist while scheming to tear apart his relationship with his beloved.

To avoid her death route, Xin Siyue carefully avoided the male and female protagonists at every turn. Instead, she went off on her own to enjoy life. But somewhere along the way, she made a mistake– the male protagonist took notice of her!

Xin Siyue’s eyes teared up as she was being kissed in Chen Sinan’s arms. ‘No! This wasn’t in the plot!’

- Description from novelupdates

Lu Changsheng, who traveled through time and became an apprentice in the Miaoshou Garden, originally wanted to work hard to be a generation of genius doctor who can help the world. But when he started to practice martial arts, he found that every time he practiced a martial art to perfection, he could improve his understanding.

Moreover, understanding seems to be able to improve all the time. Lu Changsheng wanted to know, where is the upper limit of comprehension?

Unremarkable: Slightly better than crap.

The posture of the middle man: obscuring everyone without knowing it.

Possesses great potential: Xiao He has just shown her sharp corners.

Qianlong in the Abyss: Flood Dragons Come Out of Shallow Water!

Praise from all sides: Show your sharpness, unstoppable!

Dragon and phoenix among men: The name of genius spreads all over the world!

Praise for centuries: Founding a sect and establishing a sect, calling the sect and being the ancestor!

A born sage: astonishing the past and the present, unsurpassed!

There is no one in all ages: there is no one before and no one after!

Top savvy: unspeakable, unseen, unheard!

…

The finished volumes of “Mage Profound Truth”, “Eternal Martial Arts”, “Longevity Seed”, “Old Master” and “Survival Seed” are all excellent works, produced by Lao Yue, they must be excellent!

- Description from novelbuddy