News comes to David that Saul and Jonathan are dead. David tears his clothes off, mourns, has the messenger killed, sings a song for them, and then returns to Hebron in Judah. Upon arrival in Judah, oil is dumped all over his head and word spreads around that Oily Dave, as they called him, was now the king.
Unfortunately, Saul's old General, Abner, had declared Saul's son Ish-Bosheth to be king, starting a civil war between Israel and Judah. After a while, Ish-Bosheth pisses Abner off, Abner switches sides, and David's Commander, Joab, kills him. David was also knocking up any woman that passed by him apparently, having six kids with six different women.