Toaru Majutsu no Index: New Testament - Volume 13, Afterword

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.

Li Che had transmigrated and, after living nineteen ordinary years, he opted to accept his fate, marrying and having children, striving to support his family.But the moment his daughter was born....Through his daughter, he rose in status, and his life was no longer ordinary....With his daughter’s safe birth, you gained a Dao Fruit, “Immortal Artisan”.When his daughter turned one, safe and sound, you gained the Dao Fruit “Dragon Elephant Vajra”.At his daughter's age of two, free from illness and disaster, he gained a Dao Fruit, “Pure Heart”.By the time his daughter was three, lively and clever, he gained a Dao Fruit, “Chess Saint”.His daughter was four, five, six years old.......Li Che discovered that with each passing year of his daughter’s age, he could condense a Dao Fruit to enhance himself.From then on, Li Che harbored a simple and unpretentious wish.A Dao Fruit a year, quietly safeguarding longevity.As a father, he only wished...Starting from the warmth of his wife and child by the hearth, to peacefully protect his daughter's immortality.Silently condensing countless Dao Fruits.Henceforth cultivating his spirit, invincible between heaven and earth.

She, a 21st century mercenary queen, had crossed over into a tragically betrayed body of a waste. Waste? She will show them what it means to be a waste! Betrayed? With the Ancient Manual in her hands, she will astonish all the despicable men and cheap women!

This is the story of Ryo, who was reincarnated in the world of swords and magic.It is a story of the royal road to survive using the magic of water attribute.What is magic? What is swordsmanship?How does it relate to the laws of physics that we know?Or what is politics? What is a nation?Why are there many 『kingdoms』 in reincarnation stories? Will republics not work?Can it be written …?Since it is a water-based magician, so it shall start with 『Hydrogen bond』!