Archaeologists in Concord, Massachusetts found five musket balls they say were fired on April 19, 1775 at Minute Man National Historic Park during the event famously known as "The Shot Heard Round the World."

The musket balls were discovered by archaeologists who were working in preparations for the park's Great American Outdoors Act project.

"The Shot Heard Round the World"

The National Park Service said early analysis of the 18th-century musket balls shows they were fired by colonial militia members at British forces during the North Bridge fight.

Historians say the battle marked the first time that provincial militia leaders ordered their members to fire upon soldiers from their own government.

Ralph Waldo Emerson later coined it "The Shot Heard Round the World" because of the implications the event had in escalating the conflict between colonial rebels and British forces.

Historic discovery at Minute Man National Historic Park

The musket balls were discovered in an area of the park where British soldiers formed to resist a river crossing by their opponents. According to analysis of the musket balls, they were fired from the opposite side of the river, not dropped while reloading.

"It's incredible that we can stand here and hold what amounts to just a few seconds of history that changed the world almost 250 years ago," Minute Man Park Ranger and historic weapons specialist Jarrad Fuoss said. "These musket balls can be considered collectively as 'The Shot Heard Round the World,' and it is incredible that they have survived this long. It is also a poignant reminder that we are all stewards of this battlefield and are here to preserve and protect our shared history."

The musket balls are on display Saturday, July 13 during the park's Archeology Day.