The First Order - Chapter 7 - Substitute teacher

In the twenty-ninth year of the First Emperor, Bo Langsha was attacked.

When Ying Zheng merged the memories of the 21st century history doctor, looked at the mighty mountains and rivers in front of him, and said to himself, “In this life, my Daqin can’t die!”

- Description from novelbuddy

Reborn in the early 1980s, what Lin Xia wished to do was to be “idle” to the extreme, and so wealthy that it dripped off of her...Having another chance at life, all she wanted was for her brother to live a long life of a hundred years, her younger brother to attend university, and to set up a small business for her sister;Yet, why were two highly eligible men taking turns to express their feelings for 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.

In a world where power is dictated by gangs, cities, and families ranked from Tier 1 to Tier 6, only the strongest survive. In the Tier 4 city of Blackridge, fifteen-year-old Elijah struggles to find his place. With his mother working tirelessly and his younger sister depending on him, he has always kept his head down.Determined to rise above the chaos, Elijah and his best friend Kai decide to create their own gang from nothing. But strength in this world isn’t given—it’s taken. The gangs that rule Blackridge won’t tolerate competition, and even the weakest gang has more resources, manpower, and experience than they do. With no money, no reputation, and no clear allies, they must navigate a brutal world of betrayals, violence, and ambition, where every decision could mean life or death.But Elijah is different. He possesses a mysterious system that offers him power—at a cost. As he slowly uncovers its secrets, he realizes that survival is not enough. To protect those he loves, he must become stronger than anyone else. He must climb the ranks, crush the opposition, and seize control of Blackridge’s underworld.But in a world ruled by kings, warlords, and ancient families, the price of power is steep. And when the past comes back to haunt him—when whispers of a forgotten night resurface—Elijah must confront not only his enemies but the truth about himself.In the gang world, the strong rise, the weak perish, and only the ruthless reign supreme.And Elijah? He plans to reign at the very top