If You Travel Through Time and Become a Prince, You Will Be Killed If You Don't Rebel?

I crossed the bridge and became the seventh prince. My father thought I was a fool. The prince wanted to kill me all the time. If I didn't rebel, he would be killed? You fight among yourself, I will go to the border army to secretly take power, and give you food and drinks every year. When I approach the city, you have the right to abdicate voluntarily.