As Brown released the signal rockets to start the operation, Montgomery led his column down to Wolfe's Cove, where they headed east, negotiating large blocks of ice and climbing the rocky precipice on the landward side wherever the river bank was blocked. As they neared Prés de Ville they heard the bell of Notre Dame des Victoires over the wind rousing the city. Sentries had spotted lanterns bobbing about in the swirling snow and the citizens were arming themselves.
Below the tip of Cape Diamond the column was stopped by a line of picket posts running from the river's edge to the cliff. Four were cut down and Montgomery stepped through the gap and walked to the next barrier. Taking a saw, he cut through two posts beside the cliff (to avoid enemy lines of fire) and slipped through, accompanied by a dozen officers and men. After a brief conference with his aides, Montgomery unsheathed his sword, held it aloft and led the advance across the open space between the barricade and a two-story blockhouse. The building held four small cannon manned by nine sailors and some 30 French and nine British militiamen. When the advancing Americans were about 50yds (45m) away they opened fire. Montgomery was hit in the head and killed instantly. So too were his aides, Captains Jacob Cheesemen and John Macpherson, a sergeant, and most of the men with him.
Montgomery's deputy quartermaster, Colonel Donald Campbell, was now the senior officer. Moving forward he found about 50 men at the second barricade, their muskets useless in the snowstorm. The surviving officers recommended withdrawal and Campbell agreed, taking command of the rearguard as the column fell back along the riverbank. Inside the blockhouse the occupants apparently panicked, having no idea what was happening outside. Later when news of Arnold's attack arrived, a Boston loyalist, John Coffin, used his bayonet to stop the men abandoning the post.
On the other side of the city, Arnold's column was led by 30 riflemen and Lamb's gunners with a brass 6-pdr on a sled. Behind them were the remaining riflemen, under Morgan, Steele, and Hendricks. Then came Greene's and Meigs' contingents, and finally the Indians and Canadians. A message had been sent to Dearborn on the north bank of the St Charles, but he had not shown up. Arnold could only hope he would join en route.
As the rockets went off, they moved through St Roche. Opposite the Porte Palais the main body was spotted by sentries and the whole column was struck by musketry and grenades from the ramparts. Lamb's 6-pdr was abandoned after becoming stuck in a snowdrift and the gunners became infantrymen. As the column passed through the docks it reached the first barrier across Sault au Matelot, defended by 30 militia and three cannon. Without Lamb's gun, Arnold had no option but to launch a frontal assault.
As the column surged forward, Arnold was struck in the left ankle by a ricocheting bullet. A rifleman and Chaplain Spring carried him back to Dr Senter. Almost instinctively the men turned to Morgan, who responded by leading them forward and being the first to scale a ladder. Musket fire scorched his face, knocking him off the ladder, but he climbed back up again with two riflemen, jumped onto the gun platform and rolled under one of the cannon to avoid the bayonets of the defenders. His men followed up the ladder and within minutes had captured the 30 defenders for the loss of one dead and six wounded.
