@Nope No maybe about it if the kingdom's more than a century or two old. WWI is called one big (European) royal family squabble for a reason.
The Galactic Navy Officer Becomes an Adventurer
by Takuma Tomomasa , A_Itoh
Available on mangabuddy for reading, and for sale at https://www.amazon.com/dp/B0BT6V7CMM
by Takuma Tomomasa , A_Itoh
Available on mangabuddy for reading, and for sale at https://www.amazon.com/dp/B0BT6V7CMM