Dorchester Heights, Massachusetts

views updated

Dorchester Heights, Massachusetts

DORCHESTER HEIGHTS, MASSACHUSETTS. 2-27 March 1776. As American soldiers began the siege of Boston in the days after the first clashes at Lexington and Concord (19 April 1775), they did not establish positions on either the Charlestown peninsula, across the Charles River from Boston, or the Dorchester peninsula, which extended into Boston Harbor from the southeast. Both areas remained in the no-man's-land between the opposing armies until early June, when, to forestall a British expedition against Cambridge, the Massachusetts Committee of Safety directed its forces to occupy both locations. Massachusetts Major General John Thomas was reluctant to comply, knowing the weakness of the troops under his command at Roxbury, and in the event, only Charlestown peninsula was fortified, action that led directly to the Battle of Bunker Hill.

The Dorchester peninsula remained unoccupied for the rest of the year, but it continued to play a significant role in the calculations of both sides. Indeed, the Committee of Safety understood that artillery placed on the heights near the end of the peninsula would make Boston Harbor untenable for the British as early as May 1775, when it endorsed Benedict Arnold's idea to acquire the requisite cannon from Fort Ticonderoga. The British generals in Boston also understood the importance of the heights, but after Bunker Hill they thought their army would be spread too thinly if they tried to hold it.

The stalemate began to dissolve as Colonel Henry Knox's "Noble Train of Artillery" wended its way from Fort Ticonderoga to Cambridge. General Washington had arrived at Cambridge on 2 July 1775, and ever since he had been building up the American army's stocks of gunpowder, without which the cannon would be useless. Now, with the arrival of the artillery at Cambridge in late January, and the pressing need to take some offensive action before the arrival of British reinforcements in the spring, Washington held a council of war on 16 February 1776 to discuss the matter with his generals. Although he believed the army capable of assaulting Boston, his generals did not share that opinion, and they proposed instead that the Americans seize some position and force the enemy to attack. Dorchester Heights was the obvious choice. As finally worked out, the plan was for this high ground to be fortified in the course of a single night, as had been done at Bunker Hill. Because the frozen ground made quick pick-and-shovel work impossible, Rufus Putnam proposed that the army construct fortifications aboveground by the use of prefabricated parts. Heavy timber frames (called chandeliers) were assembled, and gabions, fascines, and bales of hay were made up to fit into them. Barrels to be filled with earth were prepared to be placed around the works, where they would give the fortification an appearance of strength and also could be rolled down the steep, bare slopes into the ranks of attacking forces. Abatis would be constructed from orchards adjoining the heights.

A secondary attack across Back Bay to turn the defenses of Boston Neck was also planned should the British attack the fortifications on Dorchester Heights. For this operation, Major General Israel Putnam would lead the division of John Sullivan and Nathanael Greene: four thousand men in forty-five bateaux, supported by two floating batteries. As a diversion, American guns would start a heavy bombardment on 2 March and continue nightly through 4-5 March, when the fortifications were to be built.

The main operation was commanded by John Thomas (then a Continental brigadier general), who moved out the night of 4 March with a work detail of 1,200 men, a covering force of 800 men, and a train of 360 ox carts to move the heavy fortification materials. Conditions were ideal: the air was mild, a bright moon gave light by which to work, and a ground haze obstructed enemy observation from Boston and Castle William. Although the artillery drowned out much of the noise of shovels, picks, and axes on the hill, a British officer detected the work at 10 p.m. and reported it to Brigadier General Francis Smith. That venerable regular officer, who had shown himself to be mentally and physically slow at Lexington and Concord, did nothing. By daylight the Americans had completed their work unmolested: a fresh fatigue party had reported at 3 a.m.; the ox carts had made two trips; and reinforcements, including five rifle companies, had arrived to man the two small forts.

The American movement took Major General William Howe, the British commander in chief in Boston, by surprise. He had sent troops to raid and reconnoiter Dorchester Heights on 14 February, and when they found no American activity, he seems to have let his attention lapse. Now he may have overestimated the American accomplishment. After the works became visible, he reported to London that the Americans must have employed at least twelve thousand men to raise them. A British engineer estimated that up to twenty thousand men were involved. Still, Howe needed to act quickly, since the Royal Navy would have to pull its ships out of the harbor if the American positions were not soon eliminated. Because a bombardment was unlikely to dislodge the rebels (British gunners would have difficulty hitting men firing from behind fortifications on heights above them), Howe planned a night attack with twenty-two hundred men under Major General Valentine Jones to take Dorchester Heights with the bayonet and push on into the American lines at Roxbury, if possible. At a council of war around 7 p.m., shortly before Jones's troops were to move out, Howe and his generals agreed that the attack should be called off. Howe had already decided that Boston was a cul-de-sac and that his best chance of suppressing the rebellion required him to change his base to New York. He refused to sacrifice troops he would soon need elsewhere on what amounted to a rear-guard action. A few hours later, over the night of 5-6 March, a severe storm struck, and Howe informed his troops in general orders the next day that he had canceled the operation due to adverse weather conditions. On 7 March he began issuing orders for the evacuation of Boston.

The Americans attempted to extend their Dorchester Heights position by occupying and fortifying Nook's Hill on the night of 9 March, but they were driven off with the loss of five men dead by artillery fire. Washington and his army had demonstrated (to themselves as well as to the British) that they could strike quickly, with stealth and cleverness, but in the end the principal operational result was to speed up the British timetable for withdrawal.