First Demonic Dragon - Chapter 493 The Cave*

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.

[Complete 1V1 Pure Romance] Zhong Xiaoxiao had transmigrated. When she opened her eyes, she found herself on her wedding night, “You might as well prepare to be a widow.”Before she could understand what was happening, her cheap husband had fled, and she became the vilified and reluctantly married country bride. Life is like a dream, but one must carry on. So what if her reputation was in tatters? Rolling up her sleeves, she set to work with her whole family. When they met again, even if they couldn't get a divorce, acting as a fake married couple was still an option, right? However, as she continued to pretend, she actually fell... [New recommendation “Reborn Husband Tender Wife”]

This stands at the forefront of strategy guides to Life (a shitty video game)!

In Zhenhai City, the Chu Family receives an imperial decree that revives the hope of reclaiming their ancestral title, but only if a descendant places in the top three of the Martial Examination. For young Chu Yangxiang, who unexpectedly discovers he has Grade 1 Martial Dao Talent, this honor seems within reach. Yet, as he rises, envy and family rivalries emerge, with the privileged Chu Xiaoxiang demanding loyalty—or threatening to ruin him. Determined and battered, Chu Yangxiang faces a brutal choice: submit or fight for his family’s legacy. Will he overcome these powerful?