Answers to Questions by Yair Davidiy (28 September 2017, 8 Tishrei, 5778)
In the Bible, how was the next king of Israel decided?
In principle the monarch was chosen from the ruling family. The elder son had first option BUT if the elders were not easy with his succession another one of the male candidates would be chosen. A Prophet or the ruling council of 70 elders (the Sanhedrin) would decide. [A similar process occurs today with the succession of Chasidic Rabbis.] If the succession had been contested then after it was decided it would be confirmed by Anointment with sanctified oil. This may be seen in the succession of Solomon who was coronated while his father David yet lived. Solomon was a younger son and had an elder brother named Adoniyahu who also claimed the throne, see 1-Kings chapters 1 and 2.
Maimonides. Laws of Kings and Their Wars
Melachim uMilchamot - Chapter 1
7 When a king is appointed, he is anointed with oil reserved for this purpose, as I Samuel 10:1 states: 'And Samuel took the cruse of oil and poured it over his head. Then, he kissed him.'
Â Once a king is anointed, he and his descendents are granted the monarchy until eternity, for the monarchy is passed down by inheritance, as Deuteronomy 17:20 states 'Thus, he the king and his descendents will prolong their reign in the midst of Israel.'
If the king leaves only a young son, the monarchy should be held for him until he matures, as Yehoyada did for Yoash. The order of inheritance of the monarchy is the same as that governing the inheritance of property. An older son is given precedence over a younger one.
The above applies if the knowledge and the fear of God of the son is equivalent to that of his ancestors. If his fear of God is equivalent to theirs but not his knowledge, he should be granted his father's position and given instruction. However, under no circumstance should a person who lacks the fear of God be appointed to any position in Israel, even though he possesses much knowledge. ....
8 If a prophet appoints a king from any other tribe of Israel and that king follows the path of Torah and mitzvot and fights the wars of God, he is considered as a king, and all the commandments associated with the monarchy apply to him.