The sun set at seven o'clock on that nineteenth day of April, in 1775.[310] It never rose again on Middlesex County under kingly rule. Percy must have been in the vicinity of Union Square, Somerville, at that particular moment. The pauses for his artillery demonstration; the destruction of the few buildings; the killing of Miller; and the hurried march to the Charlestown line, did not occupy more than half an hour. It was just dark enough for the musket flashes to be seen across the marshes and across the waters of the Charles River to the Boston shore, where were grouped anxious watchers awaiting the news of battle.

Percy's thirty-six rounds for each of his soldiers had been about all expended. He describes the fire all around his marching column as "incessant," coming from behind stone walls, and from houses that he at first supposed had been evacuated.[311]

Charlestown Common, now Sullivan Square, was soon reached, and his column gladly wheeled to the right and marched up Bunker Hill. As they did so, a mile away, on top of Winter Hill, in Somerville, were just then arriving three hundred more Americans, who had marched from Salem under Col. Timothy Pickering. They were half an hour late to be particularly effective. No blame can be attached to them for that, for there were thousands of other minute-men, from distant towns who were also late, for April 19th, but who were in ample time to join the besieging army on April 20th.

At Charlestown Common, on the corner of the road to the Penny Ferry which crossed the Mystic River to Everett,[312] stood the home of William Barber, sea captain. His family consisted of his wife, Anne Hay, and their thirteen children. One of them, Edward, fourteen years old, sat at the window looking out upon the brilliant pageant of marching soldiers in the road. Many of the soldiers must have seen him, for he was not in hiding. One did, at all events, and with that thirst for killing some one, even though but a boy, shot him and saw him fall back into the room dead. Thus Edward Barber became Charlestown's martyr of April 19th.

While Charlestown did not officially contribute to the organized minute-men who were pursuing Percy, yet many individuals must have been in the American ranks on that day, for in the afternoon Gen. Gage wrote to James Russell of Charlestown that he had been informed people of that town had gone out armed to oppose His Majesty's Troops, and that if a single man more went out armed, the most disagreeable consequences might be expected. The people of Charlestown indeed had reason to be in terror, surrounded as they were by the soldiers, frenzied with their disastrous retreat from Lexington. The Selectmen arranged with Percy an armistice, agreeing that the troops should not be attacked, and that assistance should be given in getting them across the ferry to Boston, provided they would not attack the citizens or destroy their homes. This agreement seems to have been kept in good faith by both parties.[313] British officers walked up and down the streets, directing the women to keep within doors.

Percy's force remained on Bunker Hill until arrangements were completed for their trip across the Charles River to Boston. The wounded were sent over first, being conveyed by the boats of the Somerset man-of-war, which still lay there, as it did when Revere crossed the night before.

Gen. Gage sent pickets from Boston, selected from the Tenth and Sixty-fourth Regiments to do guard duty in Charlestown.[314]

Gen. William Heath, as commander of the American forces, assembled the officers of the minute-men at the foot of Prospect Hill, in Somerville, for a Council of War. Then he ordered the formation of a guard to be posted near, and sentinels along the road now known as Washington Street in Somerville, and Cambridge Street in Charlestown, to Charlestown Neck. The remainder of the force was ordered back to Cambridge,[315] which place was to be for a while the Headquarters of the American Army.