C. F. Keil and Franz Delitzsch on 2 Samuel 2:12-13

2Sa 2:12-13 War between the supporters of Ishbosheth and those of David. - 2Sa 2:12, 2Sa 2:13. When Abner had brought all Israel under the dominion of Ishbosheth, he also sought to make Judah subject to him, and went with this intention from Mahanaim to Gibeon, the present Jib, in the western portion of the tribe of Benjamin, two good hours to the north of Jerusalem (see at Jos 9:3), taking with him the servants, i.e., the fighting men, of Ishbosheth. There Joab, a son of Zeruiah, David’s sister (1Ch 2:16), advanced to meet him with the servants, i.e., the warriors of David; and the two armies met at the pool of Gibeon, i.e., probably one of the large reservoirs that are still to be found there (see Rob. Pal. ii. pp. 135-6; Tobler, Topogr. v. Jerusalem, ii. pp. 515-6), the one encamping upon the one side of the pool and the other upon the other.