When Stark was 8 years old, his family moved to Derryfield, where he lived for the rest of his long life. During King George's War, he was captured by Abenaki warriors and brought back to Quebec. While a prisoner of the Abinaki, he and his fellow prisoners were made to run the guantlet of warriors on both sides armed with sticks. John grabbed the stick out of the first warriors hands and proceeded to attack his was thought the guantlet taking the rest of the warriors by surprise. The chief was so impressed by this act that Stark was adopted into the tribe, where he spent the winter. Then next spring, a goverment agent sent from Massachusetts in Quebec to work on the exchange of prisoners paid his ransom and John returned to New Hampshire.
Stark enlisted as a second lieutenant under Maj. Robert Rogers during the French and Indian War. As part of the daring Rogers' Rangers, he gained valuable battle experience and knowledge of the Northern frontier of the American colonies. At the end of the war, he retired as a captain and returned to Derryfield.
The Battle of Lexington and Concord on April 15, 1775 signalled the start of the Revolutionary War, and Stark returned to military service. On April 23, he accepted a colonelcy in the New Hampshire Militia and was given command of the 1st New Hampshire Regiment. As soon as he could muster his men, he ferried and marched them south to Boston to support the blockaded American force there. He made his headquarters in the confiscated Isaac Royall House in Medford, Massachusetts.
On June 16, the Americans, fearing a preemptive British attack on their positions in Cambridge and Roxbury, decided to take and hold the high ground surrounding the city, including Dorchester Heights, Bunker Hill, and Breed's Hill. Holding these positions would allow them to oppose any British landing. The positions could also be used to emplace cannon which could threaten the British ships blockading the harbor.
When the British awoke on June 17 to find hastily constructed fortifications on Breed's Hill, British Gen. Thomas Gage knew that he would have to drive the Americans out before fortifications were complete. He ordered the HMS Lively, a 38-gun frigate, to begin shelling the American positions immediately and ordered Maj. Gen. William Howe to prepare to land his troops. Thus began the Battle of Bunker Hill. Col. William Prescott held the hill throughout the intense initial bombardment with only a few hundred untrained militia. Prescott knew that he was sorely outgunned and outnumbered. He sent a desperate request for reinforcements.
Stark and his New Hampshire minutemen arrived at the scene soon after Prescott's request. The Lively had begun a rain of accurate artillery fire directed at Charlestown Neck, the narrow strip of land connecting Charlestown to the American positions. On the Charlestown side, several companies from other regiments were milling around in disarray, afraid to march into range of the artillery fire. Stark ordered the men to stand aside and calmly marched his men to Prescott's positions without taking any casualties.
When the New Hampshire militia arrived, the grateful Prescott allowed Stark to deploy his men where he saw fit. Stark surveyed the ground and immediately saw that the British would probably try to flank the Americans by landing on the beach of the Mystic River, below and to the left of Breed's Hill. He led his men to the low ground between Mystic Beach and the hill and ordered them to "fortify" a 2-rail fence by stuffing straw and grass between the rails. They extended the fence by throwing up a crude stone wall.
After this fortification was hastily constructed, Stark deployed his men 3-deep behind the wall. A large contingent of British with the Royal Welch Fusiliers in the lead advanced towards the fortifications. The Americans crouched and waited until the advancing British were almost on top of them, and then stood up and fired as one. They unleashed a fierce and unexpected volley directly into the faces of the fusiliers, killing 90 in an instant and breaking their advance. The fusiliers retreated in panic. A charge of British infantry was next, climbing over their dead comrades to test Stark's line—this charge too was decimated by a withering fusillade by the Americans. A third charge was repulsed in a similar fashion, again with heavy losses to the British. The British officers wisely withdrew their men from that landing point and decided to land elsewhere, with the support of artillery.
Later in the battle, as the Americans were forced from the hill, Stark directed the New Hampshire regiment's fire to provide cover for Prescott's retreating troops. The day's New Hampshire dead were later buried in the central burying ground, Medford, Massachusetts.
While the British did eventually take the hill that day, their losses were so great, especially among the officers, that they could not hold the positions. This allowed Gen. George Washington, who arrived in Boston 2 weeks after the battle, to place his cannon on Bunker Hill and Dorchester Heights. This placement threatened the British fleet in Boston Harbor and forced Gage to withdraw all his forces from the Boston garrison and sail south.
As Washington prepared to return south to fight the British there, he knew that he desperately needed experienced men like Stark to command regiments in the Continental Army. Washington immediately offered him a command in the Continental Army. His New Hampshire regiment agreed to attach themselves temporarily to the Continental Army. Stark and his men traveled to the New Jersey colony with Washington and fought bravely in the Battle of Princeton and Battle of Trenton.
After Trenton, Washington asked Stark to return to New Hampshire to recruit more men for the Continental Army. He agreed, but upon returning home, he learned that while he was fighting in New Jersey, a fellow New Hampshire, Col. Enoch Poor, had been promoted to Brigadier General in the Continental Army. In Stark's opinion, Poor had refused to march his militia regiment to Bunker Hill to join the battle, instead choosing to keep his regiment at home. Stark, an experienced woodsman and a fighting commander, had been passed over by someone with no experience and apparently no will to fight. On March 23, 1777, Stark resigned his commission in disgust, although he pledged his aid to New Hampshire should it be needed. Four months later, Stark was offered a commission as brigadier-general of the New Hampshire militia. He accepted on the strict condition that he would not be answerable to Continental Army authority. Soon after receiving his commission, he was ordered by Brig. Gen. Philip Schuyler to depart from Charlestown, New Hampshire to reinforce the Continental army at Saratoga, New York. He refused and instead led his men to meet the British at the Battle of Bennington. Before engaging the British and Hessian troops, he prepared his men to fight to the death, shouting "There are your enemies, the Red Coats and the Tories. They are ours or this night Molly Stark sleeps a widow!"
Stark's men, with some help from the Vermont militia, routed the British forces there and prevented British Gen. John Burgoyne from being resupplyed. His action contributed directly to the surrender of Burgoyne's northern army at the Battle of Saratoga some months later. This battle is seen as the turning point in the Revolutionary War, as it was the first major defeat of a British general and it convinced the French that the Americans were worthy of military aid.
Stark became widely known as the "Hero of Bennington." After serving with distinction throughout the rest of the war, he retired to his farm in Derryfield. It has been said that of all the Revolutionary War generals, he was the only true Cincinnatus, a member of the Society of Cincinnati, because he truly retired from public life at the end of the war. In 1809, a group of Bennington veterans gathered to commemorate the battle. Stark, then aged 81, was not well enough to travel, but he sent a letter to his comrades, which closed "Live free or die. Death is not the worst of evils." The motto "Live Free or Die" became the New Hampshire state motto in 1945.