By 1775, tensions between the American colonies and the British government were reaching a breaking point.

Although the Declaration of Independence was still over a year away, preparations were already being made for what many colonists viewed as an inevitable conflict. In Massachusetts, for example, Patriots had formed a “shadow” government and were training militias to fight the British troops currently occupying Boston–and they weren’t being secretive about it. Word–and a growing sense of anxiety–made its way across stretched the Atlantic and, in the spring of 1775, General Thomas Gage, the British governor of Massachusetts, received instructions from England to seize all stores of weapons and gunpowder accessible to the American insurgents. On April 18, he ordered 700 British troops to march from Boston to Concord, a distance of about 20 miles, commandeer the arsenal there, and then capture Patriot leaders Samuel Adams and John Hancock, who were known to be residing in Lexington.

But this was exactly what the Patriots had been training for.

Cue your fifth grade history lesson on the famous “midnight ride.”

The weekend before, as if warned by some uncanny sixth sense, Patriot Paul Revere had arranged for a lantern to be displayed in the steeple of Boston’s Christ Church, which could be used to warn the militia of the British’s approach. According to Henry Wadsworth Longfellow’s poem “The Midnight Ride of Paul Revere,” the alarm would go as follows:

“One if by land, and two if by sea;

And I on the opposite shore will be,

Ready to ride and spread the alarm

Through every Middlesex, village and farm,

For the country folk to be up and to arm.”

Seeing the lanterns and learning of the British plan, Paul Revere and William Dawes set out to rouse the militiamen and warn Adams and Hancock. Along the way, the men stopped at each house, alerting the countrymen to the coming invasion. The story goes, as he approached the house where Adams and Hancock were staying, a sentry asked that he not make so much noise. “Noise!” said Revere, “You’ll have noise enough before long. The regulars are coming out!”

When the British troops arrived at Lexington at around 5 a.m. on the morning of April 19, a group of about 80 militiamen were waiting. British Major John Pitcairn ordered the outnumbered Patriots to disperse, and after a moment’s hesitation, the Americans began to drift off the green. Suddenly, a shot was fired from an undetermined gun, and a cloud of musket smoke soon covered the green. When the brief Battle of Lexington ended just minutes later, eight Americans lay dead or dying and 10 others were wounded. Only one British soldier was injured.

The Patriots had been routed. But Revere and Dawes’s warning–as well as the pandemonium caused by the short battle–had awakened Massachusetts.

The first battle was over. But the Revolutionary War was only just beginning.

When the British troops reached Concord at about 7 a.m. on the morning of April 19, they found themselves encircled by hundreds of armed Patriots. Although managing to destroy the military cache stored there, the British suffered numerous casualties at the hands of the militiamen. The commander of the British force, Lt. Col. Francis Smith, ordered his men to return to Boston without directly engaging the Americans. As the British retraced their 16-mile journey, their lines were constantly beset by Patriot marksmen firing at them from behind trees, rocks, and stone walls. At Lexington, Captain Parker’s militia had its revenge, killing several British soldiers as the Red Coats hastily marched through his town. By the time the British finally reached the safety of Boston, nearly 300 British soldiers had been killed, wounded or were missing in action. The Patriots suffered fewer than 100 casualties.

It would take seven years, 10,000 deaths, and a tangent of soldiers from all over Europe, but on April 19, 1775, the birth pangs first began in what would ultimately result in a free, independent United State of America.