שמואל ב, פרק י׳, פסוק ט״ו

A series of military defeats forced the Aramean armies to recognize the severe threat posed by Israel. The Aramean kings saw that their forces were being beaten repeatedly [אברבנאל]. They understood that David had established himself as a conquering king who was actively seeking to expand his borders. Furthermore, they knew David would not forgive them for interfering in the previous war to support the nation of Ammon [ביאור שטיינזלץ].

Driven by this realization, the Aramean kings decided to join forces. They gathered to plan their next steps and organize a coordinated counterattack [אברבנאל, ביאור שטיינזלץ]. This large-scale mobilization was based on the belief that only by amassing an enormous, unified military force could they hope to win the battle and finally defeat Israel [מצודת דוד].