Final answer:
British officials like Major John Pitcairn dismissed the idea of colonial militias defeating the British, an underestimation that would be proven wrong as the American Revolution unfolded, leading to British defeat.
Step-by-step explanation:
The idea that the colonial militias could not defeat the British in the Revolutionary War was a viewpoint held by some British officials, including Major John Pitcairn. He believed that one swift military campaign and the burning of a few towns would quell the American rebellion. This sentiment reflected the British underestimation of colonial resolve and military capability. However, subsequent events, such as the battles at Lexington and Concord, proved Pitcairn's assessment to be overly optimistic. The fierce resistance offered by the colonial militias eventually led to a prolonged conflict that culminated in British defeat.
Benjamin Franklin, expressing his outrage, also suggested that British actions, particularly the burning of towns and killing of colonists, were fierce enough to ensure that reconciliation was out of the question. The offensive initiated by General Gage was a critical spark leading to the explosive conflict that would become the American Revolution.