Final answer:
Bacon and his followers demanded a commission to lead a militia against the Native Americans due to tensions between the English colonists and the Indians in the Chesapeake colonies, particularly during the Susquehannock War.
Step-by-step explanation:
Bacon and his followers demanded a commission to lead a militia against the Native Americans as a result of tensions between the English colonists and the Indians in the Chesapeake colonies. One event that triggered this demand was the Susquehannock War, where the frontier residents preferred an offensive war against the Indians. Nathaniel Bacon, a leader of Bacon's Rebellion, sought a commission from his cousin, Governor William Berkeley, to lead forces against the Indians, but Berkeley refused. Bacon then led attacks against the Indians without the commission.