NEW YORK >> As the U.S. marks the 250th anniversary of the Battle of Bunker Hill, it might take a moment — or more — to remember why.

Start with the very name.

“There’s something percussive about it: Battle of Bunker Hill,” says prize-winning historian Nathaniel Philbrick, whose “Bunker Hill: A City, A Siege, A Revolution” was published in 2013. “What actually happened probably gets hazy for people outside of the Boston area, but it’s part of our collective memory and imagination.”

“Few ‘ordinary’ Americans could tell you that Freeman’s Farm, or Germantown, or Guilford Court House were battles,” says Paul Lockhart, a professor of history at Wright University and author of a Bunker Hill book, “The Whites of Their Eyes,” which came out in 2011. “But they can say that Gettysburg, D-Day, and Bunker Hill were battles.”

Bunker Hill, Lockhart adds, “is the great American battle, if there is such a thing.”

Much of the world looks to the Battles of Lexington and Concord, fought in Massachusetts on April 19, 1775, as the start of the American Revolution. But Philbrick, Lockhart and others cite Bunker Hill and June 17 as the real beginning, the first time British and rebel forces faced off in sustained conflict over a specific piece of territory.

A day-long reenactment of the battle got underway Saturday morning with the seaside city of Gloucester standing in for Charlestown. Organizers chose a state park some 35 miles from Boston to stage the battle because such activity is prohibited at the actual site.

Hundreds of onlookers watched as sharpshooters positioned on a rocky outcropping fired upon red-coated British sailors landing in the harbor. During the actual battle, British soldiers responded by setting a fire to drive them off and used the smoke to mask their movements.

“We’re in a volatile period, but this is a way that we can really celebrate our heritage and our diverse creation of what became America,” said Andrew Lyter, a reenactor overseeing the smaller vessels.

“I teach history at a college, and this is really neat to engage with an audience that’s very interested in being here and learning about their history,” he said.

Bunker Hill was an early showcase for two long-running themes in American history — improvisation and how an inspired band of militias could hold their own against an army of professionals.