יהושע, פרק ד׳, פסוק י״ב

Crossing the Jordan River marks a major turning point for the Israelites, specifically in how they organize themselves for travel and battle. During their long journey through the desert, the tribes marched in a strict, fixed formation. Now, as they prepare to conquer the land, their entire military and movement strategy changes.

The tribes who settled on the eastern side of the Jordan River leave their families and property behind. They step up to the very front of the nation, serving as the vanguard leading the camp. Meanwhile, the rest of the people follow behind, carrying the heavy burden of their equipment, flocks, and tents [מלבי״ם, ביאור שטיינזלץ].

As this vanguard marches forward, their readiness for war is understood in two distinct ways. One perspective suggests they are simply fully equipped with weapons, prepared for the upcoming battles [ביאור שטיינזלץ]. Another approach views their readiness as a specific method of military organization, where the soldiers are carefully divided into structured battalions of fifty men, each led by a commander [מלבי״ם].

Even though these eastern tribes promised to fight on the front lines for their brothers, not every eligible man goes into battle. The total military population of Reuben and Gad numbers over eighty-three thousand men. However, only the most elite and heroic fighters, totaling about forty thousand soldiers, actually cross the river. This select group is specially chosen from among their brothers to perfectly fulfill the original agreement they made with Moses [מלבי״ם, חומת אנך].