The siege of Boston (April 19, 1775 – March 17, 1776) was the opening phase of the American Revolutionary War. In the siege, American patriot militia led by newly-installed Continental Army commander George Washington prevented the British Army, which was garrisoned in Boston, from moving by land. Both sides faced resource, supply, and personnel challenges during the siege. British resupply and reinforcement were limited to sea access, which was impeded by American vessels. The British ultimately abandoned Boston after eleven months, moving their troops and equipment north to Nova Scotia.
The siege began on April 19 after the Revolutionary War's first battles at Lexington and Concord, when Massachusetts militias blocked land access to Boston. The Continental Congress, meeting in Philadelphia, formed the Continental Army from the militias involved in the fighting and appointed George Washington as commander in chief. In June 1775, the British seized Bunker Hill and Breed's Hill, two Continental Army positions overlooking Boston; their casualties proved heavy, roughly 1160 British and 469 Americans, and their gains were insufficient to break the Continental Army's encirclement. After this, the Americans laid siege to Boston; no major battles were fought during this time, and the conflict was limited to occasional raids, minor skirmishes, and sniper fire. British efforts to supply their troops were significantly hindered by the smaller but more agile Continental Army and patriot forces operating on land and sea. The British suffered from a continual lack of food, fuel, and supplies.
In November 1775, George Washington sent Henry Knox on a mission to bring the heavy artillery that had recently been captured at Fort Ticonderoga. In a technically complex and demanding operation, Knox brought the cannons to Boston in January 1776, and this artillery fortified Dorchester Heights, which overlooked Boston harbor. This development threatened to cut off the British supply lifeline from the sea. British commander William Howe saw his position as indefensible, and he withdrew his forces from Boston to Halifax, Nova Scotia, on March 17.
The siege of Boston (April 19, 1775 – March 17, 1776) was the opening phase of the American Revolutionary War. In the siege, American patriot militia led by newly-installed Continental Army commander George Washington prevented the British Army, which was garrisoned in Boston, from moving by land. Both sides faced resource, supply, and personnel challenges during the siege. British resupply and reinforcement were limited to sea access, which was impeded by American vessels. The British ultimately abandoned Boston after eleven months, moving their troops and equipment north to Nova Scotia.
The siege began on April 19 after the Revolutionary War's first battles at Lexington and Concord, when Massachusetts militias blocked land access to Boston. The Continental Congress, meeting in Philadelphia, formed the Continental Army from the militias involved in the fighting and appointed George Washington as commander in chief. In June 1775, the British seized Bunker Hill and Breed's Hill, two Continental Army positions overlooking Boston; their casualties proved heavy, roughly 1160 British and 469 Americans, and their gains were insufficient to break the Continental Army's encirclement. After this, the Americans laid siege to Boston; no major battles were fought during this time, and the conflict was limited to occasional raids, minor skirmishes, and sniper fire. British efforts to supply their troops were significantly hindered by the smaller but more agile Continental Army and patriot forces operating on land and sea. The British suffered from a continual lack of food, fuel, and supplies.
In November 1775, George Washington sent Henry Knox on a mission to bring the heavy artillery that had recently been captured at Fort Ticonderoga. In a technically complex and demanding operation, Knox brought the cannons to Boston in January 1776, and this artillery fortified Dorchester Heights, which overlooked Boston harbor. This development threatened to cut off the British supply lifeline from the sea. British commander William Howe saw his position as indefensible, and he withdrew his forces from Boston to Halifax, Nova Scotia, on March 17.
Background
Before 1775, the British imposed taxes and import duties on the American colonies, to which the Americans objected since they lacked British Parliamentary representation. In response to the Boston Tea Party and other acts of protest, 4,000 British troops were sent to occupy Boston under the command of General Thomas Gage and to pacify the restive Province of Massachusetts Bay. Parliament authorized Gage to disband the government of Massachusetts Bay, led by John Hancock and Samuel Adams, among numerous other powers. Still, the Americans formed the Massachusetts Provincial Congress and continued to meet. The Provincial Congress called for the organization of local militias and coordinated the accumulation of weapons and other military supplies. Under the terms of the Boston Port Act, Gage closed the Boston port, which caused much unemployment and discontent.
British forces went to seize military supplies from the town of Concord on April 19, 1775, but militia companies from surrounding towns opposed them at the Battles of Lexington and Concord. At Concord, some of the British forces were routed in a confrontation at the North Bridge. The British troops were then engaged in a running battle during their march back to Boston, suffering heavy casualties. All of the New England colonies raised militias in response to this alarm and sent them to Boston.
Order of battle
British Army
The British Army order of battle in July 1775 was:
Captain Daniel Morgan's Independent Rifle Co. (Virginia)
Siege
Immediately after the battles of April 19, the Massachusetts militia formed a siege line extending from Chelsea, around the peninsulas of Boston and Charlestown, to Roxbury, effectively surrounding Boston on three sides. The siege line was under the loose leadership of William Heath, who was superseded by General Artemas Ward late on April 20. They particularly blocked the Charlestown Neck, the only land access to Charlestown, and the Boston Neck, the only land access to Boston, which was then a peninsula, leaving the British in control only of the harbor and sea access.
The size of the colonial forces grew in the following days, as militias arrived from New Hampshire, Rhode Island, and Connecticut. General Gage wrote of his surprise at the number of Patriots surrounding the city: "The rebels are not the despicable rabble too many have supposed them to be.... In all their wars against the French they never showed such conduct, attention, and perseverance as they do now."
General Gage turned his attention to fortifying easily defensible positions. He ordered lines of defenses with ten 24-pound guns in Roxbury. In Boston proper, four hills were quickly fortified. They were to be the main defense of the city. Over time, each of these hills was strengthened. Gage also decided to abandon Charlestown, removing the beleaguered forces that had retreated from Concord. The town of Charlestown itself was entirely vacant, and Bunker Hill and Breed's Hill were left undefended, as were the heights of Dorchester, which had a commanding view of the harbor and the city.
The British at first greatly restricted movement in and out of the city, fearing infiltration of weapons. The besieged and besiegers eventually reached an informal agreement allowing traffic on the Boston Neck, provided that no firearms were carried. Residents of Boston turned in almost 2,000 muskets, and most of the Patriot residents left the city. Many Loyalists who lived outside the city of Boston left their homes and fled into the city. Most of them felt that it was not safe to live outside of the city, because the Patriots were now in control of the countryside. Some of the men arriving in Boston joined Loyalist regiments attached to the British army.
The siege did not blockade the harbor, and the city remained open for the Royal Navy to bring in supplies from Nova Scotia and other places under Vice Admiral Samuel Graves. Colonial forces could do little to stop these shipments due to the superiority of the British fleet. Nevertheless, American privateers were able to harass supply ships, and food prices rose quickly. Soon, the shortages meant that the British forces were on short rations. Generally, the American forces were able to gather information about what was happening in the city from people escaping the privations of Boston, but General Gage had no effective intelligence of American activities.
Early skirmishes
On May 3, the Massachusetts Provincial Congress authorized Benedict Arnold to raise forces for taking Fort Ticonderoga near the southern end of Lake Champlain in the Province of New York, which was known to have heavy weapons and only lightly defended. Arnold arrived in the village of Castleton in the New Hampshire Grants (Vermont) on the 9th, where he joined with Ethan Allen and a militia company from Connecticut, all of whom had independently arrived at the idea of taking Ticonderoga. This company captured Fort Ticonderoga and Fort Crown Point under the joint leadership of Arnold and Allen. They also captured the one large military vessel on Lake Champlain in a raid on Fort Saint-Jean. They recovered more than 180 cannons and other weaponry and supplies that the Continental Army used to tighten their grip on Boston.
Boston lacked a regular supply of fresh meat, and many horses needed hay. On May 21, Gage ordered a party to go to Grape Island in the outer harbor and bring hay to Boston. The Continentals on the mainland noticed this and called out the militia. As the British party arrived, they came under fire from the militia. The militia set fire to a barn on the island, destroying 80 tons of hay and preventing the British from taking more than three tons.
Continental forces worked to clear the harbor islands of livestock and supplies useful to the British. The Royal Marines attempted to stop removal of livestock from some of the islands on May 27 in the Battle of Chelsea Creek. The Americans resisted and the British schooner Diana ran aground and was destroyed. Gage issued a proclamation on June 12 offering to pardon all of those who would lay down their arms, with the exception of John Hancock and Samuel Adams, but this merely ignited anger among the Patriots, and more people began to take up arms.
Breed's Hill
The British had been receiving reinforcements throughout May until they reached a strength of about 6,000 men. On May 25, generals William Howe, John Burgoyne, and Henry Clinton arrived on HMS Cerberus, and Gage began planning to break out of the city.
The British plan was to fortify Bunker Hill and Dorchester Heights. They fixed the date for taking Dorchester Heights at June 18, but the colonists' committee of safety learned of the British plans on June 15. In response, they sent instructions to General Ward to fortify Bunker Hill and the heights of Charlestown, and he ordered Colonel William Prescott to do so. On the night of June 16, Prescott led 1,200 men over the Charlestown Neck and constructed fortifications on Bunker Hill and Breed's Hill.
British forces under General Howe took the Charlestown peninsula on June 17 in the Battle of Bunker Hill. The British succeeded in their tactical objective of taking the high ground on the Charlestown peninsula, but they suffered significant losses with some 1,000 men killed or wounded, including 92 officers killed. The British losses were so heavy that there were no further direct attacks on American forces. The Americans lost the battle but had again stood against the British regulars with some success, as they successfully repelled two assaults on Breed's Hill during the engagement.
Stalemate
General George Washington arrived at Cambridge on July 2. He set up his headquarters at the Benjamin Wadsworth House at Harvard College and took command of the newly formed Continental Army the following day. By this time, forces and supplies were arriving, including four independent companies of riflemen (not part of any state line) from Maryland and Virginia. Washington began the work of molding the militias into an army, appointing senior officers (the militias had typically elected their leaders), and introducing more organization and disciplinary measures.