SOUTH BEND, Ind. -- Indiana National Guard soldiers and airmen celebrated the 250th anniversary of the beginning of the Revolutionary War this week as they aim to continue carrying on the legacy of citizen soldiers. 

The famous "shot heard around the world" that is said to have sparked the Battles of Lexington and Concord on April 19, 1775, started the war for American independence that would rage on for the next seven years.

That first shot fired in the Revolutionary War was by a minuteman and is considered to be the first significant moment of the National Guard.

"The National Guard has adapted and evolved as necessary throughout the years - remaining just as relevant today as it was in 1775," a National Guard spokesperson said. "Those battles ignited the American Revolutionary war that helped the colonies shake off British rule."

According to the Indiana National Guard, those minutemen trace their linage to the first muster in December 1636 which became the National Guard and also predates the active-duty Army, Navy and Marine, which will also celebrate their 250th anniversary this year too.

"This is more than just history, it's the foundation of the nation we are today," said Brig. Gen. Larry Muennich Indiana's adjutant general, in a speech to his troops, which number approximately 12,000 Guardsmen. "The shot heard around the world marked the first shot fired for independence and the birth of a nation founded on liberty and opportunity for all."

Poet Ralph Waldo Emerson wrote the phrase "the shot heard around the world" in his Concord Hymn that he wrote for a monument dedication at the battle site.

"It's this monument that has come to symbolize the National Guard with a farmer carrying a musket in his right hand and his left hand on his plow, leaving behind the citizen and becoming the soldier," a National Guard spokesperson said.

According to the National Parks Service, inspiration for the 1836 Battle Monument came while planning the 50th anniversary of the war for independence in the greater Boston region. In early April 1825, the Bunker Hill Monument Association formed an agreement with the town of Concord to help fund a new monument to commemorate the fighting on April 19, 1775.

"Its legacy continues to resonate, reminding us of the sacrifices made before us and inspiring those who will continue after," said Muennich.

Indeed, that legacy continues for many who serve today including Spc. Brad Autry, of Indianapolis and a combat engineer with the Indiana National Guard's 219th Engineer Brigade, headquartered in Franklin.

"One reason I joined the National Guard is because I come from a legacy of service," said combat engineer with the Indiana National Guard's 219th Engineer Brigade Spc. Brad Autry, whose father served as a lieutenant colonel in the Indiana National Guard.

The ING says Autry's uncle, grandfather and great uncles also served in the Army and Navy going back to the Civil War.

"Indiana National Guard soldiers and airmen continue the legacy of the Massachusetts minutemen of the Revolutionary War," a spokesperson said. "Those minutemen trace their linage to the first muster in December 1636 which became the National Guard and also predates the active-duty Army, Navy and Marine, which will also celebrate their 250th anniversary this year too."