Vermont, despite its place on the map, was not one of the original thirteen colonies. It was a sliver of territory lying west of New Hampshire (from which it was separated by the Connecticut River), north of Massachusetts, and east of Lake Champlain, to the west of which lay northern New York. It had been claimed by France, though never extensively settled apart from a few forts, and was surrendered to the British, along with Quebec, in the Treaty of Paris (1763) which concluded the Seven Years' War (better known here as the French and Indian War).
Shortly after the cession of Vermont by the French, Governor Wentworth of New Hampshire began giving land grants there to settlers. King George III had a different plan. He decided to place the boundary between New Hampshire and New York at the Connecticut River, thereby giving Vermont (or, as the beneficiaries of Wentworth's munificence called it, the "New Hampshire Grants") to New York. Some of the Wentworth grantees, led by the brothers Ethan, Ira and Levi Allen, along with Seth Warner and Remember Baker, formed a militia called the Green Mountain Boys that prevented New York grantees from settling in the territory.
When hostilities between the colonists and Great Britain began in 1775, the Green Mountain Boys joined the rebel side and, along with Colonel Benedict Arnold from Connecticut, captured the British forts at Ticonderoga and Crown Point on the New York side of Lake Champlain. Later, there was a schism between Ethan Allen and Seth Warner, which led to Warner's heading the Vermont Militia and Allen leading a rump group of Green Mountain Boys in an unsuccessful attempt to take Montreal.* Allen and his contingent were captured and held prisoner by the British.**
In January of 1777, Vermont declared itself an independent republic, though allied with the colonies in the fight against the Crown. In August of that year, Warner's militia played an important role in the Battle of Bennington, in which the British General Burgoyne's forces, marching south from Quebec in an effort to split the northern from the southern colonies, suffered heavy losses that contributed to their later defeat at Saratoga, considered to be the turning point of the war. Vermont gave up its independence and became the fourteenth state in 1791.
While the song in the video above is billed as a "Revolutionary War song", in my opinion it is of much more recent provenance. Still, I like it.
*This was the first attempt by forces from what is now the U.S. (actually, the Green Mountain Boys had earlier briefly held St. John, Quebec, but quickly retreated when British troops approached) to invade what is now Canada; another happened during the War of 1812. Both times, we got whupped. I was amused to read, some years ago, that in the 1920s a group of Canadian military officers took what was billed as a good will tour of U.S. military installations, during which they drew up secret plans for an invasion. The initial thrust was to capture and hold what they called the "Albany salient." Little did they realize that any army compelled to occupy and defend Albany is an army liable to mutiny en masse.
**One of those who accompanied Allen, but who either evaded capture, escaped, or was released, was one of the more colorful minor characters in early U.S. history, Matthew Lyon. A native of County Wicklow, Ireland, he was an early settler in the New Hampshire Grants, and formed a unit of what became the Green Mountain Boys. During the course of the war, he was court martialed by General Horatio Gates for cowardice and, as punishment, made to carry a wooden sword. Despite this, he later had the distinction of serving in Congress from two states, Vermont (1797-1801) and Kentucky (1803-1811), and after that unsuccessfully tried to become a delegate from the Arkansas Territory. In 1798 he became the first person to be convicted under the alien and sedition laws, for publishing letters opposing President Adams' policies with respect to France, and was re-elected to Congress while in jail. He was also the first member of Congress to be charged with an ethics violation, accused of "indecency" for expectorating in the face of a fellow Congressman (this earned him the nickname "The Spitting Lyon"), but was exonerated. Lyon's one great contribution to history was casting the deciding vote for Jefferson when the presidential election of 1800 went to the House.