Super Supportive - TWO HUNDRED TWELVE: High Flyers

Ethan accidentally rode the wrong train and ended up in Brynhildr Magical Academy where Wizards and Witches are taught on how to use Magic.As someone who didn't have any magic powers, he thought that he would be punished for being in a place where he wasn't supposed to be. Fortunately, due to a stroke of luck, the teenage boy managed to avoid the worst case scenario, and ended up staying in the Magic Academy to learn magic.Ridiculed by many for being magically crippled, Ethan strived to adapt to his new school life with the help of his new friends, who made him realize what True Magic was all about.

What could be worse than getting married to a demon prince as a human princess for a forced truce?Being in a place surrounded by demons was like a nightmare to Aelin. Demons and humans have always despised each other after all. But things only go downhill, when her husband leaves her shortly after they spend a night together to go fight a war with unknown beings which leaves Aelin at the mercy of her enemies

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.

She is the slow-witted idiot of the Prime Minister’s Residence. Everyone bullies her. He is the most respected and unfeeling Prince, with frightening ability and absolute envy! Together, they are conferred an imperial edict of marriage.