Rebellion collapsed because Banco died to dysentery.
Explanation:
In first place, Banco's Rebellion happened because Governor Berkeley didn't retaliate against Native American, so farmers gathered where Nathaniel Bacon was elected leader.
After a while, Bacon and his army had territories in the moment he died. After Bacon's death, the rebellion didn't last long, which caused the collapse. When Berkeley's aid came, the army rebellion was weakened.