The Emperor Reigns Them All - Chapter 29 Inherit the Royal Title

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 the death of Fu Sinian, Yu Duo’s heart shattered into pieces. As his widow, she was the recipient of Fu Sinian’s massive amount of inheritance. She spent her days drowning herself with alcohol and was depressed all the time. She mourned her late husband with the companionship of her designer purses, designer jewelries, and money that could last her several lifetimes.

But only Fu Sinian knew the truth — that after his death, this woman hosted parties, lived in their mansion, drove expensive sport cars, traveled the world, and flirted with men. She was having the time of her life.

Fu Sinian wasn’t so angry that his soul dissipated; quite the contrary, he was so angry that he had come back to life!

Fu Sinian, who had come back to live, looked at the mourning Yu Duo and smiled devilishly.

“We are on! Watch me make you fall in love with me for real this time!”

- Description from Novelupdates

Once Gu Qingjiu, she was fortunate enough to be born in the “best” family, ended up having a miserable and unjust life.

Reliving her life once more, Gu Qingjiu chooses to enlist in the military and bear the toughest hardships she has ever faced. Everyone says that she’s the least possible person to join the special forces. However, she manages to prove all of them wrong.

Good-for-nothing? Who’s the good-for-nothing? Is she a good-for-nothing when she can throw all of them onto the floor in a fight? Is she a good-for-nothing when she has results better than everyone else? She’ll prove all of them wrong.

Enter Helian Niancheng, the well-known, youngest major-general in Beijing. A banishment sends him into the basic ranks in a military camp as a new recruit. From then on, he meets a person that makes him dote on and protect at all costs, his beloved. However, his beloved is only focused on fighting and killing. Major-general Helian declares this to be a very bad, a very terrible situation. Yet, Gu Qingjiu merely replies,

“Scram! Lower your gun if you dare!”

She, the “godly doctor” of an assassin organization in 21st century, transmigrated into the body of Yun Family’s abandoned, good-for-nothing Ninth Miss. Good-for-nothing? Then she’ll let the world see what a real good-for-nothing looks like. Summoners are legendary? Nothing is impossible in this world! She’ll become the first Magical Summoner.