II Chronicles - Chapter 11
Upon his return to Jerusalem, Rechavam gathered the armies of Judah and Benjamin in an attempt to force the rebellious Tribes to rejoin the nation. G-d spoke to the prophet Shmayahu and told him to tell Rechavam to stand down, as the division in the kingdom was His doing. (Rechavam wisely listened and stood down.)
Rechavam remained in Jerusalem and fortified the cities of Judah and Benjamin. He appointed leaders over these cities and stockpiled provisions and weapons in them, for use in the event of war.
Even though the kohanim and Leviim resided in cities throughout the land, when the civil war came, they made their way to Jerusalem, in the territory of Judah. That's where the Temple was, and Yeravam had "disbarred" them from their ritual duties under his rule. Yeravam had established his own priests and altars to idols; those who wished to serve G-d would sneak across the border to go to the Temple. The influx of righteous people to Judah served to strengthen Rechavam for three years. (What happened after three years? Read the next chapter!)
Rechavam married three wives that were descended from the Davidic family. He loved Maacha, the daughter of David's son Avshalom, more than all his other wives and concubines. All told, Rechavam had 18 wives, 60 concubines, 28 sons and 60 daughters. Rechavam appointed Aviya, his son with Maacha, to be his successor. Since Aviya was not the oldest, he knew that some of his other sons would object, so he wisely sent them to other parts of the country, where they would be established and comfortable with their wives and families.