[Men shouting] Voice: The want of guns is so great that no trouble or expense must be spared to obtain them.

[George Washington] Atkinson: Washington has got Boston surrounded.

The problem is, he doesn't have the big guns necessary to make the British in Boston really feel threatened.

He's got some artillery, but not enough.

They tend to be smaller field guns.

He knows that at Ticonderoga, which is several hundred miles away, there are more than 80 British guns that have been captured by Benedict Arnold and Ethan Allen.

And he tells Henry Knox, "Go to Ticonderoga, bring back whatever you can."

♪ Narrator: Henry Knox was a big, amiable 25-year-old Boston bookseller who had learned all he knew about artillery and military engineering from volumes he'd stocked in his shop and from his service in the Boston militia.

He'd earned Washington's admiration for overseeing the construction of fortifications at Roxbury.

Atkinson: Washington, who's got a very good eye for subordinate talent, recognizes that this guy-- he doesn't even have a uniform at the time-- has something about him that Washington finds appealing, and the potential that Henry Knox evinces is something that Washington recognizes immediately.

Narrator: Before setting out, Knox wrote a letter to his pregnant wife Lucy, who had fled Boston, leaving her Loyalist parents and siblings behind.

Voice: Keep up your spirits, my dear girl, and don't be alarmed when I tell you that the General has ordered me to go to the westward as far as Ticonderoga.

Don't be afraid, there is no fighting in the case.

I am going upon business only.

[Henry Knox] Narrator: Knox made his way to the captured forts and found 55 guns worth transporting-- 39 field pieces, 14 mortars, and two howitzers-- all weighing more than 64 tons.

♪ Knox's task was somehow to move them 300 miles down into the Hudson Valley, across the Berkshires, and all the way to Boston.

He had horses and ox teams haul the guns overland to the northern end of Lake George.

From there, a small fleet of barges and boats ferried them more than 30 miles against howling winds to Fort George at the southern end.

♪ Voice: I have made 42 exceeding strong sleds and have provided 80 yoke of oxen to drag them as far as Springfield, where I shall get fresh cattle to carry them to camp.

We shall have a fine fall of snow, which will make the carriage easy.

[Henry Knox] ♪ Narrator: The snow for which Knox hoped proved unpredictable, sometimes too light for his sleds to glide over, sometimes too heavy for them to move at all.

♪ Crossing the Berkshires, oxen hauled the cannon up and over mountains so tall that from their summits, Knox remembered, "We might almost have seen all the kingdoms of the earth."

♪ Wherever they went, farmers and townspeople turned out to see them.

Voice: We reached Westfield, Massachusetts, and found that very few, even among the oldest inhabitants, had ever seen a cannon.

We were great gainers by this curiosity.

For while they were employed in remarking upon our guns, we were with equal pleasure discussing the qualities of their cider and whiskey.

John P. Becker.

Narrator: As the ox train lumbered on, Knox hurried ahead alone to Cambridge.

He reported to Washington that over the next few weeks, all the artillery he'd been promised would be at his disposal.

♪ When the last of Knox's cannon reached Washington's army, England's hold on Boston was doomed.

Atkinson: It's one of the most extraordinary expeditions in American military history.

He appears back in Cambridge, says, "Boss, I'm here.

"I've brought back 50 guns.

"They're parked right outside of town.

They're available whenever you need them."

Washington says, "You're my man."

And he puts Knox in charge of Continental Artillery.

[Drumbeat] Narrator: On the night of March 4th, 1776, some 3,000 men and 300 teams worked to put 20 or more heavy guns in place on Dorchester Heights.

[Drumbeat continues] Voice: March 5th.

This morning at daybreak, we discovered two redoubts on the hills on Dorchester Point, and two smaller works on their flanks.

They were all raised during the night, with an expedition equal to that of the genie belonging to Aladdin's wonderful lamp.

From these hills they commanded the whole town, so that we must drive them from their post, or desert the place.

[British officer] Narrator: Unwilling to sacrifice any more men, General Howe decided to leave Boston for Halifax in Nova Scotia, where he hoped to regroup.

♪ With him went 10,000 soldiers and their dependents as well as 1,100 Loyalist men, women, and children who would have to build new lives in a new place.

Among them were Henry Knox's in-laws.

"I have lost," his wife Lucy wrote, "my father, mother, brother, and sisters."

♪ Voice: How horrid is this war?

Brother against brother and the parent against the child.

Who were the first promoters of it, I know not.

But God knows.

And I fear they will feel the weight of His vengeance.

♪ Tis pity, the little time we have to spend in this world, we cannot enjoy ourselves and our friends, but must be devising means to destroy each other.

Lucy Knox.

♪