Fort Ticonderoga, along Lake Champlain in northeastern New York, was in a strategic position between Canada and the Hudson River Valley. Nevertheless, the British, who may not have taken the rebellious Americans seriously, chose to defend it lightly, with a garrison of only about 50 men.

The Green Mountain Boys, a Vermont-based militia, decided to take advantage of the British short-sightedness. At dawn on May 10, a force of less than 100 militiamen, led by Ethan Allen and Benedict Arnold, crossed the lake and surprised the still-sleeping British. It was the first real victory of the Revolutionary War, and boosted the colonists’ morale. Even more importantly, the Americans were able to seize and repurpose the fort’s cannons and transport them to Boston, for use in the siege of British-held Boston.

Without that artillery, the early part of the Revolutionary War might have taken a very different course, according to Lycoming College history professor Christopher Pearl, author of Conceived in Crisis: The Revolutionary Creation of an American State.

“There would most likely have been a much fiercer struggle during the siege of Boston, giving the British army the ability to successfully advance on American positions,” he explains. “Instead, with the guns in hand, the rather ragtag American army created a formidable siege that forced the British to evacuate the city.“

Though the British won the Battle of Bunker Hill on June 17, 1775, American militiamen inflicted heavy losses. With boosted confidence, the Americans continued their efforts to take the city of Boston from the British. In January 1776, the Americans were able to bring in 50 cannons seized from Fort Ticonderoga and set them up in fortifications around Boston.

In early March, they bombarded the city’s British defenders for two straight days, and General George Washington moved several thousand troops into position at Dorchester Heights, overlooking the city and its harbor. British General William Howe realized that his troops were in an indefensible position and withdrew, ending an eight-year-long occupation of Boston.

In the winter of late 1776, the Americans were in a tough position. After losses at the battles of White Plains and Forts Washington and Lee, General George Washington’s army had to retreat from the pursuing British across New Jersey and take refuge in Pennsylvania. Washington and his troops camped out along the banks on the west side of the Delaware River, where soldiers tried to rekindle their zeal by reading Thomas Paine’s pamphlet The American Crisis, which exhorted them not follow the example of “the summer soldier and the sunshine patriot” who melted away when times got tough. “The harder the conflict, the more glorious the triumph,” Paine wrote.

Washington knew that the American forces needed to make a bold move to reassert themselves. On Christmas Eve 1776, he loaded 2,400 men into boats and crossed the icy Delaware, and then marched 10 miles in the darkness to Trenton, where at dawn, they caught a garrison of 1,500 Hessian troops by surprise. While some of the German soldiers managed to escape, most were captured, and their commander, Colonel Johann Rall, was shot and mortally wounded. The remaining Hessians surrendered to Washington, giving the Americans a desperately needed victory.

At Saratoga, one of the most decisive battles of the Revolution, the Americans defeated British troops advancing southward from Canada, and prevented them from seizing control of New York’s Hudson River Valley. As British General John Burgoyne and an army of about 7,500 British soldiers headed south, American General Horatio Gates and thousands of Americans awaited him at Bemis Heights, just south of Saratoga, where they had built fortifications and positioned cannon.

The British, who were reinforced by 500 German soldiers, sustained heavy casualties in the initial confrontation on September 19, and found themselves trapped in the wilderness with a dwindling supply of food. Desperate for a way out, Burgoyne mounted a second attack on October 7, but the Americans—whose ranks by then had swelled to 13,000—pushed him back.

General Benedict Arnold (who was still on the American side at the time), led a charge that captured a German redoubt, even though Arnold sustained a serious leg wound in the process. After trying unsuccessfully to flee, the British surrendered on October 17.

“Without a doubt, the Americans could not have won the war without their great victory at Saratoga,” explains Willard Sterne Randall, a professor emeritus of history at Champlain College and author of numerous books, including the upcoming The Founders’ Fortunes: How Money Shaped the Birth of America.

“It convinced the French that with their aid, the Americans could defeat the British.” French cannons at Saratoga proved decisive, Randall notes, just as the French fleet ultimately helped seal the Americans’ victory at Yorktown a few years later.

Kings Mountain is not a well-known battle of the Revolutionary War, but it was critical to stopping the momentum that British General Charles Lord Cornwallis had built by capturing Charleston, South Carolina in May 1780. A few months after that victory, Cornwallis sent Major Patrick Ferguson to recruit a loyalist militia to protect Cornwallis’ flank as he advanced through the South. But Ferguson ran into a tough, resourceful foe—American militiamen from the South Carolina backcountry and Appalachian Mountains, who were crack shots and skilled in stealthy movement.

The two forces—900 Americans commanded by Colonel Isaac Shelby and others, and 1,105 under Ferguson on the British side—met on a rocky hilltop in western South Carolina. The Americans attacked Ferguson’s position from all sides, shooting Ferguson off his horse and killing him, and his force surrendered after suffering heavy casualties.

“Until Kings Mountain, it looked to everyone like the British were correct to see the South as the revolution’s soft underbelly,” explains Woody Holton, a professor of history at the University of South Carolina, and author of Liberty Is Sweet: The Hidden History of the American Revolution. In addition to disrupting Cornwallis’ plans, the battle also demonstrated that American riflemen could fire, retreat and reload quickly enough to defeat a British bayonet charge, according to Holton. That provided them with a potent new technique.

When the British fought on to establish control of the South, American General George Washington sent forces headed by General Nathaniel Greene into South Carolina to thwart them, leading to the critical battle of Cowpens.

Greene dispatched a contingent of 1,065 led by Brigadier General Daniel Morgan to south of the Catawba River, on a mission to cut British supply lines. To counter Morgan, British Commander General Cornwallis sent a force of 1,150 men commanded by Lieutenant Colonel Banastre Tarleton, an elite officer with a brutal reputation for allowing his forces to massacre Americans who tried to surrender.

Tarleton chased Morgan’s forces, but didn’t have good intelligence about how many men the Americans had—a disadvantage that proved critical. The two sides confronted one another at Cowpens, a pasture near Thicketty Creek. In a crafty move, Morgan organized a line of his men to fire a couple of volleys and then retreat, creating the illusion that the Americans were fleeing in panic. When The Tarleton’s forces chased them, they ran into a withering barrage of gunfire from another line of American riflemen that Morgan had hidden, followed by a cavalry attack lead by William Washington, a distant cousin of George Washington, that routed the British.

The defeat at Cowpens forced Cornwallis to give up his effort to take South Carolina. He pursued Greene’s men into North Carolina, where he defeated Greene at the Battle of Guilford Courthouse in March 1781. But Cornwallis’ army was so depleted at that point that he had to return to Virginia to rest and re-equip his soldiers. That created an opportunity for General Washington to trap him, and set up the Battle of Yorktown.

After six years of war, the British and the Americans were like a pair of exhausted boxers, struggling to make it through the final round. The British were beset by a lack of public support at home, while the Americans were burdened with war debt, food shortages and sagging morale. Something had to give. General George Washington decided to go for a knockout.

Washington had the option of attacking the British occupiers in New York City, but instead, he and Lt. General Comte de Rochambeau, who had thousands of French soldiers under his command, opted to march south to Yorktown, Virginia, where General Cornwallis and his 9,000 troops were resting.

As 8,000 American and French soldiers headed to Virginia, the French fleet defeated the British Navy in the Battle of the Capes and seized control of the mouth of the Chesapeake Bay, preventing British ships from coming to Cornwallis’ rescue. By late September, Washington and de Rochambeau had reached Yorktown, where they were joined by another nearly 12,000 militia and American and French soldiers.

They dug trenches around the fortifications that Cornwallis had built to protect his army. Then, a few weeks later, the Americans began bombarding the British. On the night of October 14, the Americans and French attacked the British redoubts, capturing some of the fortifications. On October 17, the British sent an officer with a white handkerchief to discuss surrender terms, and two days later, the last major battle of the Revolution was over.

Yorktown “sapped Britain’s will to fight a long war,” notes Carroll Van West, a professor of history at Middle Tennessee State University. The following March, the British Parliament passed legislation authorizing peace negotiations. Americans had won the war.