The colonial commanders knew the British were coming. On June 13, word reached the Massachusetts Provincial Congress that British generals Howe, Clinton, and Burgoyne -- all freshly arrived in Boston with reinforcements -- were planning to seize the high ground on the Charlestown Peninsula and the Dorchester Heights, positions from which artillery could dominate the harbor and the besieged city. The colonists moved first. On the night of June 16, Colonel William Prescott led roughly 1,200 men across the narrow Charlestown Neck and onto the peninsula. They were supposed to fortify Bunker Hill, but Prescott and General Israel Putnam chose Breed's Hill instead -- closer to Boston, more defensible, and more provocative. Through the night they dug furiously, building a square redoubt with earthen walls six feet high and a wooden firing platform inside. When a British sentry aboard a warship spotted the fresh fortification around four in the morning, HMS Lively opened fire. The cannonade had little effect against the elevated earthworks, but it announced to both sides that the fight was on.

General Howe chose a frontal assault. He was confident -- the hill was 'open and easy of ascent,' he assured his fellow officers -- and he expected the colonial position to collapse at the sight of disciplined British regulars advancing in line. The reality was something else entirely. The afternoon of June 17 was hot, and the redcoats marched uphill through waist-high uncut hay that hid rocks, holes, and crisscrossing rail fences. They carried full packs weighing roughly sixty pounds, wholly unnecessary for a quick assault. Their wool uniforms trapped the summer heat. Across the harbor, Charlestown was burning -- British incendiary rounds had set the town ablaze to clear snipers -- and the smoke rolled above the battlefield like a stage curtain. Behind the rail fence on the colonial left, Colonel John Stark planted a stake fifty paces out and ordered his New Hampshire men: no one fires until the British pass it.

The first British attack ended in carnage. The colonists held their fire until the redcoats were almost on top of them, then unleashed volleys that shredded the advancing lines. Howe's light infantry, marching in column along the narrow beach to turn the colonial flank, were cut down before they could deploy. Grenadier commander James Abercrombie fell mortally wounded. On the opposite flank, Brigadier General Pigot's regiments stopped to exchange fire with the colonists and were savaged by their exposed position. Both wings retreated. The second assault fared no better. British officers later wrote that their companies lost three-quarters of their men on presenting themselves, some retaining only eight or nine soldiers. After thirty minutes of futile volleys, Pigot pulled back again. For the third attack, Howe stripped his men of their packs, reformed them in tight columns instead of extended lines, and ordered a bayonet charge straight at the redoubt. This time, the colonists had run out of ammunition. The fighting became hand-to-hand, bayonet against musket butt. Colonel Prescott parried thrusts with his ceremonial sabre. Joseph Warren, president of the Massachusetts Provincial Congress serving as a volunteer private, was killed in the retreat. The British finally held the hill.

The British had taken the ground, but at staggering cost. Of the roughly 2,200 regulars who fought that afternoon, 1,054 became casualties: 226 dead and 828 wounded. One hundred commissioned officers were among the fallen, a catastrophic blow to Britain's leadership in America. General Clinton recorded in his diary a paraphrase of Pyrrhus of Epirus: 'A few more such victories would have shortly put an end to British dominion in America.' Colonial losses were far lighter -- about 450 total, with 140 killed, most during the retreat. Only thirty colonists were captured, nearly all with grievous wounds. The disparity was a revelation. Untrained farmers behind dirt walls had inflicted casualties at a rate that no professional European army would have found acceptable. The British never attempted another frontal assault on prepared colonial positions during the war.

News of Bunker Hill rippled outward in two directions, each wave carrying a different message. In the colonies, it was initially reported as a defeat -- the hill had been lost, after all. But when George Washington, traveling to Boston to take command of the Continental Army, learned the casualty figures, he recognized something more important: his side could fight. Across the Atlantic, the numbers shocked the British military establishment and hardened King George III against reconciliation. The Continental Congress had just sent the Olive Branch Petition, a last attempt at peace; the King rejected it. Within weeks, the Proclamation of Rebellion was issued. The battle's tactical lessons were just as consequential. The British shifted to cautious, flanking maneuvers and began hiring Hessian mercenaries to replace irreplaceable losses. The colonists learned that earthworks and fire discipline could neutralize professional training. Today a granite obelisk stands on the site in Charlestown, commemorating a battle fought on the wrong hill, named after the wrong hill, and won by the wrong side -- yet decisive in convincing both armies that this revolution would not end quickly.