Charlestown Neck is a narrow isthmus, connecting the peninsula with the main land; having the Mystic River, about half a mile wide, on the north, and a large embayment of Charles River on the south or right side. It was now necessary to proceed with the utmost caution, for they were coming on ground over which the British kept jealous watch. They had erected a battery at Boston on Copp's Hill, immediately opposite to Charlestown. Five of their vessels of war were stationed so as to bear upon the peninsula from different directions, and the guns of one of them swept the isthmus or narrow neck just mentioned.
Across this isthmus, Colonel Prescott conducted the detachment undiscovered, and up the ascent of Bunker's Hill. This commences at the Neck, and slopes up for about three hundred yards to its summit, which is about one hundred and twelve feet high. It then declines toward the south, and is connected by a ridge with Breed's Hill, about sixty or seventy feet high. The crests of the two hills are about seven hundred yards apart. On attaining the heights, a question rose which of the two they should proceed to fortify. Bunker's Hill was specified in the written orders given to Colonel Prescott by General Ward, but Breed's Hill was much nearer to Boston, and had a better command of the town and shipping. Bunker's Hill, also, being on the upper and narrower part of the peninsula, was itself commanded by the same ship which raked the Neck. Putnam was clear for commencing at Breed's Hill, and making the principal work there, while a minor work might be thrown up at Bunker's Hill, as a protection in the rear, and a rallying point, in case of being driven out of the main work. Others concurred with this opinion. Gridley marked out the lines for the fortifications; the men stacked their guns; threw off their packs; seized their trenching tools, and set to work with great spirit. So spiritedly, though silently, was the labor carried on, that by morning a strong redoubt was thrown up as a main work, flanked on the left by a breastwork, partly cannon-proof, extending down the crest of Breed's Hill to a piece of marshy ground called the Slough. To support the right of the redoubt, some troops were thrown into the village of Charlestown, at the southern foot of the hill.
At dawn of day, the Americans at work were espied by the sailors on board of the ships of war, and the alarm was given. The captain of the Lively, the nearest ship, without waiting for orders, put a spring upon her cable, and bringing her guns to bear, opened a fire upon the hill. The other ships and a floating battery followed his example. Their shot did no mischief to the works. The cannonading roused the town of Boston. General Gage could scarcely believe his eyes when he beheld on the opposite hill a fortification full of men, which had sprung up in the course of the night. He called a council of war. The Americans might intend to cannonade Boston from this new fortification; it was unanimously resolved to dislodge them. How was this to be done? A majority of the council, including Clinton and Grant, advised that a force should be landed on Charlestown Neck, under the protection of their batteries, so as to attack the Americans in rear and cut off their retreat. General Gage objected that it would place his troops between two armies; one at Cambridge, superior in numbers, the other on the heights, strongly fortified. He was for landing in front of the works, and pushing directly up the hill; a plan adopted through a confidence that raw militia would never stand their ground against the assault of veteran troops.
The sound of drum and trumpet, the clatter of hoofs, the rattling of gun-carriages, and all the other military din and bustle in the streets of Boston, soon apprised the Americans on their rudely fortified height of an impending attack. They were ill-fitted to withstand it, being jaded by the night's labor, and want of sleep; hungry and thirsty, having brought but scanty supplies, and oppressed by the heat of the weather. Prescott sent repeated messages to General Ward, asking reinforcements and provisions. Ward issued orders for Colonels Stark and Read, then at Medford, to march to the relief of Prescott with their New Hampshire regiments.
In the meantime, the Americans on Breed's Hill were sustaining the fire from the ships, and from the battery on Copp's Hill, which opened upon them about ten o'clock. They returned an occasional shot from one corner of the redoubt, without much harm to the enemy, and continued strengthening their position until about eleven o'clock, when they ceased to work, piled their intrenching tools in the rear, and looked out anxiously and impatiently for the anticipated reinforcements and supplies. The tools were ultimately carried to Bunker's Hill, and a breastwork commenced by order of General Putnam. The importance of such a work was afterwards made apparent.
About noon the Americans descried twenty-eight barges crossing from Boston in parallel lines. They contained a large detachment of grenadiers, rangers, and light infantry, admirably equipped, and commanded by Major-general Howe. A heavy fire from the ships and batteries covered their advance, but no attempt was made to oppose them, and they landed about one o'clock at Moulton's Point, a little to the north of Breed's Hill. Here General Howe made a pause. On reconnoitering the works from this point, the Americans appeared to be much more strongly posted than he had imagined, and he immediately sent over to General Gage for more forces. While awaiting their arrival, refreshments were served out to the troops. The Americans meanwhile took advantage of the delay to strengthen their position. The breastwork on the left of the redoubt extended to what was called the Slough, but beyond this, the ridge of the hill, and the slope toward Mystic River, were undefended, leaving a pass by which the enemy might turn the left flank of the position, and seize upon Bunker's Hill. Putnam ordered his chosen officer, Captain Knowlton, to cover this pass with the Connecticut troops under his command. A novel kind of rampart, savoring of rural device was suggested by the rustic general. About six hundred feet in the rear of the redoubt, and about one hundred feet to the left of the breastwork, was a post and rail-fence, set in a low foot-wall of stone, and extending down to Mystic River. The posts and rails of another fence were hastily pulled up, and set a few feet in behind this, and the intermediate space was filled up with new mown hay from the adjacent meadows. This double fence, it will be found, proved an important protection to the redoubt, although there still remained an unprotected interval of about seven hundred feet.
While Knowlton and his men were putting up this fence, Putnam proceeded with other of his troops to throw up the work on Bunker's Hill, despatching his son, Captain Putnam, on horseback, to hurry up the remainder of his men from Cambridge. By this time Stark made his appearance with the New Hampshire troops, five hundred strong. Putnam detained some of Stark's men to aid in throwing up the works on Bunker's Hill, and directed him to reinforce Knowlton with the rest. About two o'clock, Warren arrived on the heights, ready to engage in their perilous defence, although he had opposed the scheme of their occupation. He had recently been elected a major-general, but had not received his commission. Putnam offered him the command at the fence; he declined it, and merely asked where he could be of most service as a volunteer.
The British now prepared for a general assault. An easy victory was anticipated; the main thought was, how to make it most effectual. The left wing, commanded by General Pigot, was to mount the hill and force the redoubt, while General Howe, with the right wing, was to push on between the fort and Mystic River, turn the left flank of the Americans, and cut off their retreat. General Pigot, accordingly advanced up the hill under cover of a fire from field-pieces and howitzers planted on a small height near the landing-place on Moulton's Point. His troops commenced a discharge of musketry while yet at a long distance from the redoubts. The Americans within the works, obedient to strict command, retained their fire until the enemy were within thirty or forty paces, when they opened upon them with a tremendous volley. Being all marksmen, accustomed to take deliberate aim, the slaughter was immense, and especially fatal to officers. The assailants fell back in some confusion; but, rallied on by their officers, advanced within pistol shot. Another volley, more effective than the first, made them again recoil. To add to their confusion, they were galled by a flanking fire from the handful of Provincials posted in Charlestown. Shocked at the carnage and seeing the confusion of his troops, General Pigot was urged to give the word for a retreat.
In the meantime, General Howe, with the right wing, advanced along Mystic River toward the fence where Stark, Read, and Knowlton were stationed, thinking to carry this slight breastwork