MTL - Chaotic Lightning Cultivation - ~ 856th Kaitenjin Ax

He was the continent’s strongest and most revered alchemist, Ye Zifeng. He was under one person and above millions. However, due to an unpredictable event, he had died. After his rebirth, he had become the supertrash of the Ye family and suffered disgrace. To make matters worse, he had an argument with his fiancé that led to the break off of his engagement. In this second life, he will work to change his own destiny. He vows to return to the peak of the world, trample on those who laughed at him and rewrite his legacy!

- Description from Novelupdates

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.

[Post-apocalyptic + System Space + Stockpiling + Base Building + Strong Female Lead + Reverse Harem + Not a Mary Sue]Who says a five-year-old can only be a burden?Cloud Xiaoxiao, a formidable survivor in the post-apocalyptic world, is reborn six days before the apocalypse hits. Unloved by both parents and unwanted after their divorce, she decides to take matters into her own hands.At just five years old, she goes on a rampage. She empties out her father’s supermarkets and 4S car dealerships, landing him in the hospital.Armed with a super system in a world ravaged by zombies, extreme temperatures, and acid rain, she hoards enough supplies to last several lifetimes. She becomes a base-building maniac, constructing the strongest fortress in the post-apocalyptic world.Sunny Boy Next Door: “Little one, want big brother to sing you a lullaby?”Unlucky Bandit: “Kid, what do you want? I’ll get it for you.”Cool Big Brother: “Don’t be afraid. I’m here.”Yandere Hottie: “Little one, call me big brother and I’ll kill them all for you. How about that?”Hot-Tempered Brawler: “Shorty, who’s bullying you? I’ll beat them to death!”…Cloud Xiaoxiao hastily raises her hand, “Stop, stop! I can take on ten at once!”“Whoever dares to bully me, I’ll finish them off myself!”(This story has no romantic pairings. Readers who mind this, please be cautious.)(The female lead appears innocent on the outside but is actually a wolf in sheep’s clothing. Her personality was shaped by the post-apocalyptic world, growing beyond the bounds of normal rules. So she’s a bit ruthless, a bit wild, a bit wicked…)

Qin Guan was reborn and sent back to his final semester in High School 18 years ago. Getting a second chance at life, he works hard to turn things around and eventually become a Prince Charming. What will his life be like the second time around? What will he have to go through? How will he succeed in turning from a loser into a Prince Charming?