The deafening sounds of war and the frantic galloping of fleeing horses echo the complete shattering of Sisera's military power. During the panicked retreat from the flooding river, the sheer force and repetitive pounding of the horses' flight proved to be their undoing. The primary approach among commentators is that as the horses fled, the intense impact of striking the ground crushed and broke the ends of their legs, leaving them entirely without strength to continue [מצודת דוד, רלב״ג]. Because the heel of a horse lacks a protective hoof, this specific area was exceptionally vulnerable, making the physical damage devastating and absolute [רד״ק]. The relentless pounding highlights the massive number of horses and the raw intensity of their flight [רש״י, מצודת ציון, רד״ק]. In this chaotic scene, the mighty ones leading the charge are understood to be either the heroic riders desperately guiding the retreat or the powerful horses themselves [מצודת דוד, רד״ק].
Beyond the physical toll of the retreat, other commentators connect the destruction of the horses directly to the forces of nature. Intense heat radiating from the stars boiled the mud on the battlefield as well as the soldiers' armor. Seeking relief from the heat or attempting to escape, the horses waded into the waters of the Kishon River. The sudden, sharp clash with the water caused their hooves to detach and tear off, as if they had been boiled in scalding water, completely shattering their legs [רש״י, אברבנאל]. Adding to this physical ruin was a massive wave of chaos orchestrated by God within the enemy camp. Gripped by confusion and terror, the galloping horses turned into weapons against their own army, trampling and crushing their riders and crashing into one another as they fled [אלשיך]. The thunderous sound of their frantic escape could be heard from far away [ביאור שטיינזלץ].
From a unique poetic angle, some interpret the galloping mighty ones not as Sisera's horses, but as the raging waves of the Kishon River itself. These crashing waters are compared to charging horses that battered the enemy chariots and ultimately drowned them [מלבי״ם]. On a deeper historical and symbolic level, the destruction of Sisera's horses represents a profound historical closure. Sisera's chariots are viewed as the remnants of Pharaoh's chariots from Egypt. Therefore, their watery end in the Kishon River symbolizes the final, absolute defeat of the heavenly prince of Egypt, a spiritual force that is itself likened to a horse [אהבת יהונתן].