According to the divine right theory, how do leaders gain the right to rule?

They derive their right from God Himself.. No man on earth gives them the right.

most of the knowledge we have of the conflict comes from roman-jewish scholar titus flavius josephus, who first fought in the revolt against the romans, but was then kept by future emperor vespasian as a slave and interpreter.

the right answer is the end of world war ii

after the end of a global wwii all the nations involved, in an attempt to create an organization to maintain world peace. this agreement would work settling international disputes via negotiation and arbitration instead of leading the issues escalate to another war.