Sunday, February 24, 2019

Episode 085: Dorchester Heights

When we last left Cambridge at the end of January 1776, Colonel Henry Knox had successfully returned with the cannon from Fort Ticonderoga.  But Washington and his generals still did not have a clear plan in place for how to use them.

How to Attack Boston

For months, Washington had been arguing for a direct assault on Boston.  He proposed a plan where wanted to have the army row across Boston Harbor in small boats, land in the face of enemy fire, and then assault the town.  His generals convinced him that this would be suicide.  Even if the soldiers did not break and run in the face of deadly artillery from the British Army and Navy, they would be cut to pieces before they could reach the shore.  Even if they somehow reached the shore and surprised the enemy, an urban combat battle much like Quebec but on a larger scale would almost certainly result in the capture or massacre of the Continentals.

On February 13, 1776, the British launched an evening raid across the ice, attacking Dorchester Neck.  Col. Alexander Leslie led several hundred regulars on the The raid burned a few houses, captured a few unlucky sentries, and then retreated back to Boston before the Continentals could react. This raised the concern that it was a prelude to a full British assault on Dorchester Heights.

A few days later, on February 16, Washington held another council of war with his generals. With the harbor frozen, he proposed  to march the army across the ice in a direct assault on Boston.  Again, all of his his generals resisted such a battle, arguing that it would be suicide.  Washington, usually calm and restrained, was clearly frustrated that he could not convince his generals to engage in a frontal attack.

Artemas Ward (from Wikimedia)
Over these same months, General Artemas Ward, the army’s second in command had argued that the best strategy would be to occupy Dorchester Heights.  This was high ground consisting of two hills on a peninsula just south of Boston.  Placing artillery on the heights, would give the Continental Army the ability to bombard the army in Boston as well as the navy in the harbor.  They would be at that elevation, the British would not be able to return fire effectively.  It would force the British to come out of Boston, either over the heavily fortified neck, or conduct a water landing then retake the heights by force.  Even if they could take the heights, it would almost certainly be at a terrible cost, making the battle of Bunker Hill look small in comparison.  The charge up the hill would not just be against militia with muskets.  The British would face a line of Continental canon.

The British had considered trying to capture the heights in summer of 1775.  It was the planned assault to take Dorchester that motivated the patriots to occupy Bunker and Breed’s Hills to the north and provoke that battle instead. After those losses, British General Gage and following his departure, General Howe did not want to risk another horrific loss trying to occupy Dorchester Heights.  Instead, they used threats to intimidate the Continentals from occupying it, leaving it a valuable no man’s land for months.

With spring approaching though, and now with a pile of heavy cannon to mount on the heights, the Continental generals agreed that it was time to occupy Dorchester Heights.  With a twist.  Washington agreed to occupy Dorchester.  If the British moved out of Boston to the south to attack Dorchester, Washington wanted to use that distraction to have his army row across the harbor from the north sending his army directly into Boston.  The council of war generally agreed to this plan.  One strong dissenter was General William Heath who thought that even if Howe sent half his army to attack Dorchester, there would still be thousands of entrenched British infantry and hundreds of army and navy cannon blasting away at militia trying to row across a mile and a half of open water to attack the city.  Heath was sure it would be a disaster and a bloodbath.  But everyone seemed to think they had to do something, and this was the best plan that drew a consensus.  The first step would be occupying Dorchester Heights.

Making a Plan

The problem was how to do it.  Mounting cannon on the heights could take weeks, or even months with the ground frozen solid.  There was no easy way to dig entrenchments without the enemy seeing what they were doing and sending out an army to take the heights before the Continentals were ready to defend it.

To tackle this problem. General Heath reached out to Rufus Putnam, a Massachusetts native and cousin of General Israel Putnam.  Rufus Putnam had worked with British engineers during the French and Indian War, but was not what you would call an expert in the science of military engineering.  After meeting with Washington to discuss the plan, Putnam decided to stop by Heath’s house on his way home.  While visiting, Putnam noticed a book on Heath’s table by a British Military Engineer called Attack and Defense of Fortified Places.

Rufus Putnam (from Wikimedia)

Putnam asked if he could borrow the book but Heath refused, saying he never lent out his books.  Putnam pointed out that Heath had stuck him with this job despite his lack of knowing anything about military engineering.  Now he had to build a fortification and Heath had the only book around that might explain how he could do it.  Really? You won’t let me read it? Finally, Heath agreed and let Putnam borrow the book.

A few pages in, Putnam saw the solution to his problem.  His men could not dig entrenchments in the frozen soil.  However, the book suggested building “chandeliers”.  In the terms of 18th century military engineering, a chandelier was a wooden frame.  Once built, the defenders filled the frame with sticks and branches, then covered the whole thing with dirt.  This created a defensive wall that would stop most bullets.

The soldiers could pre-build the chandeliers, then carry them up to Dorchester Heights at night, fill in the sticks and dirt, then mount the cannons.  With enough men, they could build a credible defensive wall and mount cannon in a matter of hours.

Putnam took the plan to Washington, who also conferred with Colonel Knox.  Of course, Knox would have to man the artillery once mounted there.  Washington also conferred  with Colonel Richard Gridley, still the Continental Army’s chief engineer.  All agreed it was a sound plan and supported it.  The only added suggestion was to add barrels filled with dirt or rocks as part of the defenses.  In addition to providing cover, if the British tried to storm the hill, the Continentals could roll the barrels  down on them, killing some and breaking up the attacking lines.


Even with a plan, it would not be easy to execute.  The first step was to put hundreds of men to work building the wooden frames.  They also set to work building 45 flat bottomed boats, which could carry 80 men each.  Washington planned to use these for his assault on Boston.  With all this work, the British would almost certainly know the Continentals were up to something.  Next, the chandeliers would have be carried across Dorchester Neck, in plain view of the enemy.  If the British realized the Continentals were planning to occupy Dorchester Heights, they could rush out and storm the heights before the defenders were ready.
Chandelier packed with Fascines (from Salina Baker)

To avoid this problem, the Continentals set up large hay bales to block the road from view in Boston.  To cover the sound, they planned to start a cannonade against Boston from other locations.  This, they hoped, would distract the regulars and prevent them from hearing the sounds of hundreds of carts hauling equipment and guns up to the heights.

General Ward took charge of building the chandeliers and other prefabricated defenses that would be carried up to the heights.  Washington invited Colonel Thomas Mifflin, who was at this time Quartermaster General, to assist with logistics.  Mifflin proposed the night of March 4th for the occupation.  That way, if the British attacked the following day, it would be the anniversary of the Boston Massacre.  Others, thought that date was a mistake.  It’s not clear why, but possibly because it was a full moon, making it easier for the British to spot the work.  In any event, the council decided to adopt the date by a single vote.

Occupying the Heights

Colonel Knox had his artillery begin an attack on Boston on the night of March 2.  The plan was to continue the bombardment on the next two nights, so that by the night of March 4, the British would be focused on the artillery, but not find it so unusual that they would suspect it was being use to cover the sounds of thousands of infantrymen occupying Dorchester Heights and installing the chandeliers and mounting the cannon.

The Continentals still did not have much gunpowder, making their cannons of limited use.  The British Navy at New York had been blockading the harbor.  But they cut a deal, allowing merchant vessels to enter there in exchange for New York providing them with fresh food to feed the sailors. Taking advantage of this, the patriots smuggled in 3000 pounds of gunpowder on February 29.  They then hauled the powder overland on wagons up to Washington’s army, just in time for use in this action.

Map of Boston during Siege, 1776 click to zoom (from Reddit)
But even that amount of powder would not last long with artillery.  Since the first night was mostly about rousing the enemy, they fired a total of only around two dozen shots into Boston.  Sadly, the patriots did more harm to themselves than the enemy.  Knox’s inexperienced artillerymen destroyed three mortars and one cannon through improper use.  A British officer in Boston noted no significant damage to anything.  Of course, the barrage triggered a response from the regulars who used their own artillery to bombard Continental camps for several hours.

The next night, March 3, Knox’s artillery once again fired on Boston.  At least this time they did not damage any of their own weapons.  Once again, the British responded.  When the Continentals opened up again on the third night, March 4, the British again returned fire, but did not suspect anything else would be different that night.

The night of March 4, turned out to be an exceptional choice.  It would not be the last time that an unusual weather occurrence helped the patriots.  A bright moon helped the patriots with their labors in getting the defenses in place on Dorchester Heights.  But the bright moon did not help the British detect them, as a haze fell over the harbor, preventing the regulars from seeing much of anything across the water.

Col. Mifflin arranged for 350 ox carts to pull all the equipment up the heights beginning shortly after sundown.  They next sent 800 soldiers to occupy the heights, just to sit there with muskets and watch for any attack from the regulars in Boston.  Half of them sat near shore, watching for an attack from Castle Island.  The other half watched for an attack from Boston Neck.

Washington gave the task of emplacing all the artillery and entrenchments to Gen. John Thomas who organized 1200 more troops to do the work.  Washington himself appeared on the heights to encourage the men and see that everything went according to plan.  Colonels Knox and Gridley also worked on site, making sure everything was installed where it was planned.

But remember, occupying the heights was only half of Washington’s plan.  Washington fully expected the British to discover the occupation, either that night or certainly by morning, and that they would then scramble to launch an offensive force out of Boston to take the heights.  As soon as they did that, Washington had 4000 soldiers under the command of General Israel Putnam, ready to launch two raiding parties under the command of Generals Greene, and Sullivan.  These men would row across Boston Harbor, landing on the north side of town, fight their way through the city and link up with the soldiers on the south side commanded by General Ward at Roxbury.  For the moment, these men were just sitting and waiting for a signal that the regulars were attacking Dorchester Heights.

Dorchester Heights (from Twitter Boston NPS)
The plan seemed to move along with no significant problems.  By 10:00 PM, they had established two forts on the heights, and continued with the installation of chandeliers along the line.  Several hours before dawn, everything was in place and ready to go.  In total, if you count the guards, the men building the fortifications and those hauling the material to the site, there were a little over 3000 men involved.

Now, you may remember during the battle of Bunker Hill, no one made any attempt to relieve the men who built the entrenchments overnight, nor did anyone set up supply lines to bring them food and ammunition.  The Continentals did not make that same mistake at Dorchester.  In the morning, 3000 fresh troops came up to replace the men who had spent all night building the defenses.  But it turned out the men who did the digging did not want to let the next shift get the glory of going to battle.  Most of the night shift stayed on the heights as well, leading to as many as 6000 defenders.  By morning, the Continental Army was fully embedded on the heights, with all the infantry and artillery they needed to repulse any assault.

British Reaction

In Boston, General Howe, had received intelligence from deserters that the Continentals were planning something on Dorchester, but he did not know the date or other details.  Rather than act proactively, Howe waited until they actually did something.  He would then assault the heights while they were building the defenses.

During the night, while the Continentals secretly built the defenses, at least one officer in Boston detected activity and reported to his superior that the rebels were occupying the heights.  That superior was General Francis Smith, the same man who had led the original expedition to Lexington the previous April.  General Smith had always been a “follow orders” kind of officer, who did not grab the initiative or act with great energy.  In this case, he decided he would take up the matter with General Howe in the morning.

When dawn broke, the regulars were shocked to see not one, but two fully-built forts, and a line of entrenchments, complete with cannon, built on the top of Dorchester Heights.  According to one account, Howe said it would have taken his army months to complete such an emplacement.  Howe’s chief engineer estimated it must have taken 15,000-20,000 men to build those works overnight.

The British immediately turned their artillery fire on the new defenses but found that they were too high for them to hit effectively, either from Boston or from ships in the harbor.  At the same time, the Continentals could lob shots into the city or at naval vessels in the harbor unopposed.

Dorchester Heights
(from Twitter SW O'Connell)
Despite the entrenchments being pretty well in place, Howe launched a contingent of soldiers that morning to take the heights.  British General Valentine Jones loaded a force of just over 1200 men into boats to take them over to the Dorchester Peninsula.  They planned to attempt a water landing, in the face of cannon, musket, and rifle fire, then form up and charge the hills, defended by as many as 6000 patriots.  In other words, the British would have only a fraction of the force they had an Bunker Hill, and faced a much larger force supplemented by artillery.  This really seemed like a suicide mission.

Fortunately for the British attackers, the weather once again intervened.  High winds kicked up and prevented the force from being able to land before high tide that morning.  Once the tide was coming out, it would be even harder to effect a landing.  So, they got the force to Castle Island and planned a nighttime attack during the next high tide, just after midnight.  But the storm kicked up again even worse with hurricane force winds preventing any landing.

The following day, wind and rain continued, making a landing still nearly impossible.  Howe convened a council of war, at which just about every officer argued against an attack.  The rebels had had another 24 hours to make their defenses even stronger and there was no realistic way they were going to take the heights.

Although Howe had received reinforcements all winter, he was also losing men at a fair clip due to smallpox and other diseases.  He also had allowed Gen. Clinton to leave with some of his regulars to go conquer the Carolinas.

General Howe had maybe 6000 men ready for duty.  Even if he sent all of them against Dorchester, it probably would not have been enough to dislodge an entrenched enemy.  At the same time, and all out attack would encourage Washington to launch his invasion of Boston from the north side of the harbor.  There was just no way for Howe to win this one.

A frustrated General Howe agreed with the council of war that an attack would never work.  He admitted he only planned to order the attack for the honor of the army.  Now, accepting that plan was a pointless waste of lives in a no-win situation, Howe called off the attack completely.

This may have been a good thing for the Continentals too.  If Howe had launched his attack against Dorchester, Washington likely would have launched his ill-conceived amphibious attack on Boston.  The regulars almost certainly would have cut down that 4000 man attack force, leading to a terrible defeat for Washington.  It might even have led to his dismissal as Commander in Chief.  None of that happened though.  When Howe called of his attack, Washington called off his as well.

No attack though, meant Howe was stuck in a situation where the rebels could fire on the army and navy at will without the British being able to return fire effectively.  Well before all this happened, Howe had determined that the army should evacuate Boston and move down to New York as the center of operations.  Howe had hoped to make that move in a few more months, later in the spring, and after more reinforcements arrived from Britain.  Now he would have to move up that timetable.  He would also have to evacuate under the embarrassment of an amateur rebel army having out maneuvered him and forcing his retreat.

- - -

Next Episode 86: The Evacuation of Boston

Previous Episode 84: The Battle of Moore's Creek Bridge

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Further Reading


What forced the British to Leave Boston?

Baker, Salina The Taking of Dorchester Heights, 2018:

Dorchester Heights, National Park Service:

Council of War Feb. 16, 1776:

Letter from Lt. Col. Rufus Putnam, to George Washington  Feb. 11, 1776 re: Dorchester Heights:

Free eBooks
(from unless noted)

Blake, Francis Dorchester Neck. (Now South Boston.) The raid of British troops, February 13, 1776,
Boston: David Clapp & Son, 1899.

Brooks, Noah Henry Knox, a Soldier of the Revolution, New York: G.P. Putnam's Sons, 1900.

Buell, Rowena (ed) The Memoirs of Rufus Putnam, Boston: Houghton & Mifflin Company, 1903.

Dana, Elizabeth Elery (ed) John Barker diary - The British in Boston, 1774-1776, Cambridge: Harvard Univ Press, 1924.

Drake, Francis The Life and Correspondence of Henry Knox, Boston: Samuel B. Drake, 1873.

Force, Peter American Archives, Series 4, Vol 4, Washington 1837.

Force, Peter American Archives, Series 4, Vol 5, Washington 1837.

French, Allen The Siege of Boston, New York: Macmillan, 1911.

Frothingham, Richard History of the Siege of Boston, Boston: CC Little & J. Brown, 1851.

Martyn, Charles The life of Artemas Ward, the first commander-in-chief of the American Revolution, New York: Artemas Ward, 1921.

Muller John The Attack and Defence of Fortify'd Places, Woolwich: Royal Academy of Artillery, 1757 (Google Books).

Neeser, Robert (ed) The despatches of Molyneux Shuldham, vice-admiral of the Blue and commander-in-chief of His Britannic Majesty's ships in North America, January-July, 1776, New York: Naval Historical Society, 1913.

Books Worth Buying
(links to unless otherwise noted)

Beck, Derek The War Before Independence: 1775-1776, Naperville, Ill: Sourcebooks, 2016.

Fleming, Thomas 1776: Year of Illusions, New York: W.W. Norton & Co., 1975 (book recommendation of the week).

Lockhart, Paul The Whites of Their Eyes, New York: Harper Collins, 2011.

McCullough, David 1776, New York: Simon & Schuster, 2005.

Philbrick, Nathaniel Bunker Hill: A City, A Siege, A Revolution, New York: Penguin Books, 2013.

Puls, Mark Henry Knox: Visionary General of the American Revolution, New York: St. Martin's Press, 2010.

Smith, David Whispers Across the Atlantick: General William Howe and the American Revolution, Oxford: Osprey Publishing, 2017.

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