=Fortunes of the Two Hebrew Kingdoms.= David's authority evidently extended to a point about five miles north of Jerusalem. The city of Gibeon^{ (93)} was on its northern border. This important town was situated on a height two thousand five hundred and thirty-five feet above the ocean, a little west of the main northern highway and on the southern side of the two main roads that led up from the Valley of Ajalon across the central plateau to the Jordan. Part way down the regularly rounded hill on which the village stood was a spring, forming a large pool. Here, in this border town, the warriors of Joab, David's general and those of Abner fought the fatal duel which was characteristic of the border warfare of this period. The Bithron, the ravine through which Abner and his men retired to Mahanaim, was probably the Wady Ajlun east of the Jordan. The result of the battle was indicative of the waning power of the house of Saul and of the growing strength of David. It is also probable that during this period he was still a vassal of the Philistines and so enjoyed immunity from their attacks. He was thus able to develop and organize the resources of his kingdom. On the other hand, the divided northern kingdom was constantly exposed to attack from the warlike Philistines on the west and from the Ammonites on the east.
=The Final Struggle with the Philistines.= The assassination of Ishbaal by his own followers left the northern tribes no deliverer but David. All his previous training had prepared him for this great task. His acceptance of the fealty of the northern tribes was equivalent to a declaration of war against the Philistines. Regarding this important period, the biblical records are unfortunately incomplete; but from incidental references it is clear that the Philistines did not yield their claim to central Palestine without a severe and prolonged struggle. At one time they were in possession of David's own city, Bethlehem, and he was obliged again to take refuge in the border fortress of Adullam. As at the beginning of the war, they appear to have seized the series of strong fortresses on the northern border of Judah and thus to have cut off the Hebrews of the north from those of the south. The Canaanite cities from Gezer to Jebus, which doubtless acknowledged the Philistine suzerainty, completed the wall of separation.