The Substitute Bride - Chapter 19

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.

As someone who had always aspired to live a laid-back life, Xu Lin received the news of his hometown’s old house’s demolition at the age of 24. As a result he would be compensated with about 5 million. But before he could grasp the feeling of being a second-generation displaced person , he blinked and found himself back in the green years of being 17.Now, he had to embrace the “salted fish” state once again and wait for another 7 years. Despite his initial thoughts, a peculiar thing happened due to a confession incident, disrupting his plans.[Congratulations Host on activating the Twelve Zodiac Love System!]Thus his fate became entangled with 12 different types of girls…

Ethan, a high school student that died alongside his bully transmigrated into another world.Ethan awakened in a parallel world, one where supernatural talents determined your worth, and the talentless serve as expendable cannon fodder.Born talentless in this new world, Ethan finds himself assigned as cannon fodder against the monster hordes that threaten humanity.But his death in the previous world seemed to have granted him a supreme Talent.Follow the story of Ethan as he awakens the strongest talent and strives to become the world's Strongest.

Arthur Grail, a hardcore player of the VRMMO Trinity Star Online, woke up one day in the body of Gerard Astoria—a petty villain fated to die before the main story even began. To make matters worse, Gerard's death was a crucial event in the game's narrative. If he didn’t meet his predetermined end, it could disrupt the story entirely, leading the universe toward one of the countless “bad end” routes!Unwilling to leave his fate to chance, Arthur decided to take matters into his own hands—recruiting the “player” as his partner to help him clear the game and rewrite his destiny.But wait—“Why is the player not a dude but a sharp-tongued beauty instead?!”Follow Arthur's odyssey, filled with trouble at every turn, as he works to uncover the mystery behind his awakening in a universe eerily similar to Trinity Star Online's setting, all while trying to save the entire universe… without forgetting to enjoy himself!