In the months following the outbreak of war, American leaders hoped the Revolution might spread beyond the thirteen colonies.

Many Patriot leaders believed French-speaking Canadians living in the recently conquered Province of Quebec might join the colonial resistance against Britain. Some Americans assumed the Canadians, who had only come under British rule after the French and Indian War, would resent British authority and support the revolutionary cause.

Military leaders also recognized the strategic importance of Canada.

If British forces used Canada as a base for invasion into New York and New England, the northern colonies could face enormous danger. Capturing Quebec and Montreal might eliminate that threat while expanding American control farther north.

In 1775, the Continental Congress approved an invasion of Canada.

The campaign involved two separate American forces. One army under General Richard Montgomery moved north through New York toward Montreal, while a second expedition led by Colonel Benedict Arnold traveled through the wilderness of Maine toward Quebec City.

The campaign quickly became one of the Revolution's most difficult early operations.

Arnold's march through the Maine wilderness proved especially brutal. Soldiers faced freezing temperatures, disease, starvation, swollen rivers, and nearly impassable terrain. Food supplies ran dangerously low, and many men became too weak to continue.

Despite enormous hardship, Arnold's surviving force eventually reached Quebec.

Meanwhile, Montgomery captured Montreal after British defenders withdrew from the city. The two American forces then joined together outside Quebec City during the winter of 1775.

The Americans hoped a rapid assault might capture the city before British reinforcements arrived.

On December 31, 1775, during a snowstorm, American forces attacked Quebec.

The assault ended in disaster.

British defenses held firm while difficult weather and confusion disrupted the American attack. General Montgomery was killed during the fighting, and Benedict Arnold was wounded. Many American soldiers were captured, and the invasion stalled.

Although American forces continued the siege for several months, disease and expiring enlistments steadily weakened the army. Smallpox spread through the camps, killing or disabling many soldiers.

In the spring of 1776, British reinforcements finally arrived.

The Americans were forced to retreat southward out of Canada, ending hopes that the province would join the Revolution.

The failed invasion carried important consequences.

It demonstrated the enormous logistical challenges facing the Continental Army and revealed how difficult sustained military operations would become during the war. The campaign also showed that many Canadians remained unwilling to join the rebellion against Britain.

At the same time, Benedict Arnold's leadership during the expedition earned widespread admiration despite the campaign's ultimate failure.

The Revolution was becoming a war fought across vast distances under harsh conditions, where disease, weather, supply shortages, and geography often proved as dangerous as enemy soldiers.

As the American effort in Canada collapsed, British leaders prepared new operations aimed directly at the heart of the colonies themselves.

The next major campaign would center on one of the most important cities in America: New York.