Jamieson, Fausset and Brown on 2 Samuel 15:12

12. Absalom sent for Ahithophel--who he knew was ready to join the revolt, through disgust and revenge, as Jewish writers assert, at David's conduct towards Bath-sheba, who was his granddaughter.

Giloh--near Hebron.

the conspiracy was strong--The rapid accession of one place after another in all parts of the kingdom to the party of the insurgents, shows that deep and general dissatisfaction existed at this time against the person and government of David. The remnant of Saul's partisans, the unhappy affair of Bath-sheba, the overbearing insolence and crimes of Joab, negligence and obstruction in the administration of justice--these were some of the principal causes that contributed to the success of this widespread insurrection.

2Sa 15:13-37. David Flees from Jerusalem.