I Became Friends with the Second Cutest Girl in My Class (WN) - Chapter 21: Her Familiar Back

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.

After being fired, Lu Qingjiu finally decided to return to his hometown to farm.

At first, he started raising a pig, and then he found that the pig could solve more high-level math questions than he could.

After that, he started raising a flock of chickens, and then he found that his own fighting ability was one-tenth of that of a single chicken.

Finally, Lu Qingjiu finally realised that this old home wasn’t quite right… Especially a certain person by his side who constantly stared at him day in and day out.

Lu Qingjiu: “Are you drooling because of the spicy stir-fry I’m holding or because of me?”

Bai Yuehu pointed at the stir-fry.

Lu Qingjiu: “Then can you let go??”

Bai Yuehu reluctantly glanced at Lu Qingjiu’s arm, before loosening his teeth.

- Description from Novelupdates

Jacob Steve, an Old Man, died at 116 after living a whole life.

But Jacob always had a dark side, which he always suppressed and hid from others.
However, in the later years of his life, when death was inevitable, he understood there wasn't any point in having wealth, knowledge, or desires if you couldn't have a life to enjoy them.

He became obsessed with fabled immortality and devoted his reaming life to extending his fleeting lifespan, but just like any other failed.

However, he mysteriously got another chance at life and found a way that led to fabled immortality.
But he was also forewarned that the way led to it was filled with blood and darkness!

In the end, Jacob chose it anyway with no way of going back, and it was also the start of his suffering and his icky, brutal journey toward the 'Immortality' he wanted so badly!

Mo Poor never thought that he would suddenly have supernatural abilities until he shot an arrow towards the sun. The absolute hit means that he can be the god on the pitch, the god of the basketball world, the big Luo Jinxian in the game… He can easily become a winner in life, spend his life magnificently, and wealth and power will not be difficult . Just as he was using this to change his destiny and enjoy his life, he met the inmates who claimed to be from the Blue and White Society… When he understood this organization that executes necessary evils in the dark of the world and maintains human security, he found his true identity Goal: I want to become the president of Lanbai. The contents of this book, D-class personnel nouns and inspirations are derived from works on wikidot. And released according to CCBY-SA3.0.

- Description from novelbuddy