My Amnesic Ex Married My Sister, So I Married His Uncle - Chapter 146: Back! Back! 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.

I gave them my everything.My time… my strength… my heart.I trained while they slept.I smiled when they laughed.I stayed… even when it hurt.And what did I get?Nothing.They looked at me like I was pathetic.Like, I didn’t belong.Like I was… less.But I... the naive person I am, continued trusting them.They told me to act like trash, fine—I became trash.They told me to act like a scumbag, fine—I played the role.However...One mistake, one single moment...That’s all it took.And they threw me away.But now…Someone else woke up in my body.A stranger, a man who doesn’t know the pain I suffered, but wears my face.Let’s see what he does with it.Because me?I’m done with this life, so to the soul who took over my body...This is your mess now…'Gray'.

“If I told you about the darkness inside of me, would you still look at me like I'm the Sun?”******Annalise's life changed the very night she was married off to the Dark Lords who resided in the Cursed Castle. She was offered to them as a sacrifice to save their Empire.No one knew anything about those residing inside the Cursed Castle except that there were three of them, all men, and they all were very powerful.There was a dark force invading the peaceful lives of the people of Seelie Empire, people were disappearing and unseen things were happening. And the High Priestess confirmed that the Seelie Realm would need the help from the Dark Lords to win this battle against the unknown.Annalise ended up becoming the pawn as the only unmarried girl with royal lineage and the title of a Princess. To show their sincerity about the treaty, the royal family offered her hand in marriage to the Dark Lords, and to everyone's surprise, the Lords agreed. But they had a condition - she needed to marry all three of them!To save her Empire and people, Annalise agreed to marry all three Lords only to find that none of them showed up at the wedding.How was Annalise going to handle her married life, and her three husbands who were not only handsome beyond words but also more powerful and mysterious than people thought? Especially when they had a great battle to fight!

Uchiha Kai has been cautious since he came to this world. He vowed that he must be cautious and go to the end.

But one day he received a mission – to cover the wave wind team to blow up the Kamabashi Bridge, Uchiha Kai knew that he was going to be unlucky…

- Description from novelbuddy