Dearborn was also among those asigned to make Canada the 14th colony. The plan was for Gen. Montgomery to inch his way north from Ticonderoga. Meanwhile Col. Benedict Arnold would lead an expedition through uncharted Maine wilderness, meeting Montgomery at Quebec. Arnold's army of 1100 men, including Dearborn, set out for the Kennebec on September 19, 1775.

The march became an horrendous venture. Days of torrential rains turned the march to the first French settlement into a nightmare. Raging floods made river channels difficult to find. Dearborn and his men lost their way. Others broke through ice and slogged through waist-high water in dense swamps. Starvation and death from exposure stalked the badly bruised army, already greatly diminished in size. Several men forced Dearborn to surrender his dog, which they quickly devoured. When they arrived at the first settlement, Dearborn was too ill with pneumonia to continue with the army to Quebec. He recovered sufficiently, however, to join them for the battle on the last day of 1775. In the disaster, Montgomery was killed, Arnold wounded, and the confused army, blinded by snow, lost its way. Dearborn and much of the Army became prisoners.

Victory At Ticonderoga

Paroled in March 1777, Maj. Dearborn was on hand for the retreat from Ticonderoga to Bemis Heights. As men and supplies poured into camp, a strong line of defense was erected for control of the Hudson River. During these preparations, Dearborn was given a special command of the light infantry. The first battle, on September 19th, ended with neither side the victor. But Morgan's riflemen and Dearborn's light infantry almost annihilated Burgoyne's advance guard.

Self-assured for the second engagement, on October 7th, Morgan and Dearborn furiously drove Burgoyne's advance back to the British line. Supported by several regiments and inspired by the timely arrival of the dashing, impetuous Arnold, the Americans took the enemy's strongest redoubt causing the rest of the British line to collapse. This resounding American victory marked the turning point of the American Revolution and brought badly needed French assistance.