The first US troops to fight for America did it on this day in 1775

There has long been a dispute between the towns of Lexington and Concord over which fight sparked the Revolution, but the first shots were fired at Lexington, which was less of a battle and more of a massacre. The debate was so fierce that President Ulysses Grant almost avoided the centennial celebrations there to avoid the issue. Taken together, however, there is little doubt that the spark of the Revolution started on this day in April, 1775.

The Battles of Lexington and Concord were the first military engagements of the American Revolution, pitting members of the Massachusetts Bay Colony militia against British regular army forces. The militia was not under the royal governor, but controlled by the rebel Massachusetts Provincial Congress.

Seven hundred British troops were dispatched from Tory-held Boston to capture and destroy rebel arsenals at Concord, Mass. The rebels knew the British would come and had already moved the weapons and supplies. The British force moved through Lexington on the way to Concord.

At first light on April 19, 1775, the Redcoats met some 70 colonial militiamen moving into ranks on the local common. They were vastly outnumbered. Their commander, John Parker, was not willing to risk his men at such odds, and so placed them in formation, but not blocking the road to Concord. He ordered his men not to fire unless fired upon.

Rather than just march on to Concord, a British Marine lieutenant led his men onto Lexington Common to disarm the militia. Instead of disarming, the colonists moved to disperse. That's when a shot rang out from an unknown source. Before this encounter, there was no war declared in the colonies. The British had come and gone to seize arms and supplies many times, retreating back to the major cities each time. This time was different.

The idea of Americans in open rebellion against the British Crown was likely a shock to the subject of the British Empire. At the time of the Battles of Lexington and Concord, the British controlled territory on every inhabitable continent across the globe. Down on Lexington Common, however, those opening salvos left eight Americans dead and an equal number injured, along with one injured British regular. The engagement soured the chances of reconciliation between the colonies and the Crown.

The British would continue to Concord, where the Battle of North Bridge in Concord would kill two colonists and three Redcoats. The British retreated all the way back to Boston and were harassed by colonial militias the entire way home.

Poet Ralph Waldo Emerson composed the "Concord Hymn" in 1837, immortalizing the two events for the unveiling of a battle monument at Concord's North Bridge.

"By the rude bridge that arched the flood/Their flag to April's breeze unfurled/Here once the embattled farmers stood/And fired the shot heard round the world."

This story would one day lead to the defeat of the British at the hands of a Franco-American force, the birth of America, and eventually, School House Rock.