Isekai Maou to Shoukan Shoujo no Dorei Majutsu - Volume 4 Chapter 1 part6

She was reborn in the 1970s, when there were no mobile phones or TVs, people lived in poverty and marriages were arranged by families. He, the wealthy and powerful head of the regiment, who governed the local army, helped her join the army so that her family would no longer be bullied and could live a good life. And Suddenly, he proposed marraiage to her...

Liang Ning had just bid farewell to her eldest and second eldest brothers who died on the battlefield, never expecting that when she was preparing to fulfill a marriage contract with an orphan she saved six years ago, she would be burned alive by him!Upon waking, she became Miss Fu of the Fu Family, and her murderer had already risen to a high position, surrounded by beautiful wives and concubines, becoming a trusted minister before the emperor...No fear!Miss Liang of the Liang Family changes lanes, still the decisive and ruthless Rashamon!But why does that brat, who used to play around with her nephew and knew nothing about respecting elders, keep pestering her?

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.

Lin Yi failed the college entrance exams and chose a diploma mill university.

And as deserving of a diploma mill university, the first line of the admission letter read:

- Description from Novelupdates