The downfall of a powerful ruler often begins not on the battlefield, but within the walls of his own palace. The collapse of the King of the South, the ruler of Egypt, is brought about through a devastating combination of internal betrayal and a crushing military defeat by the King of the North.
The destruction originates with those closest to the southern king, specifically the individuals who eat his royal food and share his table [רש״י, מצודת ציון, שטיינזלץ]. These trusted figures are identified as his own ministers [רש״י, מצודת דוד], his royal courtiers [אבן עזרא], or his hired mercenaries [שטיינזלץ]. Instead of protecting their leader, these close associates turn against him and orchestrate his ruin. They act with deep deceit, plotting to hand him over to the King of the North [מצודת דוד], with some even actively seeking to take his life [יוסף אבן יחיא].
This treachery from within guarantees disaster on the battlefield. The primary approach among commentators is that the southern king's army is completely washed away and destroyed by the forces of the King of the North, leaving many soldiers slain in the conflict [מצודת דוד, אבן עזרא, יוסף אבן יחיא]. Another perspective suggests that the southern army actually launches a fierce offensive charge, yet despite their forward assault, they still suffer massive casualties and fall dead in great numbers [שטיינזלץ]. Ultimately, after this period of intense bloodshed and severe military defeat, the King of the South and the King of the North are destined to reach an agreement and make peace with one another [אבן עזרא].