Military campaigns against heavily fortified enemies require more than just human strength and strategy; they demand an absolute reliance on divine assistance. When facing an impenetrable fortress that can only be conquered through a prolonged siege, human limits become painfully clear [רד״ק, מצודת ציון, ביאור שטיינזלץ]. Historically, this daunting challenge was embodied by Bozrah, the heavily guarded capital and central stronghold of Edom [רש״י, מלבי״ם].
The journey to conquer such a formidable target involves two distinct phases of movement. The initial march to the borders of Edom is something the warriors can accomplish on their own two feet, moving forward under normal guidance. However, actually penetrating the walls of the fortress is an entirely different matter. For this impossible task, the soldiers cannot rely on their natural power. Instead, they must be carried, almost as if lifted upon God's shoulders, because human strength alone is not enough to breach the defenses [מלבי״ם, מצודת ציון].
Commentators offer two distinct ways to understand the timing of this military reflection. One approach views this as a look back at past victories. The leader reflects on the successful conquests of the fortified cities of the Philistines, Moab, and Edom, asking who guided him to subdue these nations. The clear, undeniable answer is that God alone orchestrated these triumphs [רד״ק, מאירי, מצודת דוד].
Conversely, another perspective reads these thoughts as an anxious look toward the future. Facing the looming threat of Edom's fortresses, the leader wonders who will help him lay siege and secure a victory. He recognizes that if God does not assist him, no one else can lead him to success [רש״י]. He reassures himself that the same God who guided him in the past is the only One who can help him now. Yet, this realization is accompanied by a deep sense of distress. He is acutely aware that his armies are ultimately helpless, entirely incapable of achieving anything unless God actively joins them on the battlefield [אבן עזרא].