Final answer:
The attack on Quebec failed due to Colonel Arnold's misjudged potential French Canadian allies, strong British defenses, harsh winter conditions, disease, and extended supply lines.
Step-by-step explanation:
The American Revolutionary War saw the ill-fated attack on Quebec due to several factors. One key reason was Colonel Benedict Arnold's intent to align with French Canadians against British rule, believing they would be ideal allies. Despite the French influence remaining strong after Britain's successful colonization of Canada, the alliance hoped for by American forces did not solidify as expected.
Underestimation of the strong British defense and inadequate support from the local populace contributed to a formidable challenge for the Americans. Arnold's forces were also plagued by harsh winter weather, long supply lines, and smallpox, further debilitating the campaign. These critical factors culminated in a well-defended British victory despite the Americans attempting to limit British control in North America.