Secretary of State William F. Galvin unveiled a new exhibit on Monday at the Commonwealth Museum on Dorchester’s Columbia Point that focuses on the pivotal role the colonists of Massachusetts played in the American Revolution as the nation prepares for the 250th commemoration of many of the war’s major events.

In his remarks, he said the exhibition is a timely reminder of the sacrifices made to win American freedoms.

The display, which includes rarely seen artifacts like letters and other documents owned and preserved by the state, is called “Upon Such Ground: Massachusetts and the Birth of the Revolution.”

Galvin chose Monday to unveil the exhibit as it lined up with the 249th anniversary of the day in 1776 when colonial forces forced the British to evacuate Boston after a siege of almost a year.

“The reason we are beginning it here on the edge of the Atlantic Ocean in Massachusetts is because the revolution began here,” said Galvin, who was joined by co-curators Michael Comeau, John Hannigan, and Robert Allison.

“The three of us, along with the team of many people, were able to put together a pretty interesting interpretation of this very important impact here,” said Comeau.

Some of the history is tied directly to Dorchester, Galvin noted.

“The war in Massachusetts came to an end because of the cannons on Dorchester Heights,” Galvin said. “General Washington took command of the Continental Army and brought the cannons here, put them up there, and basically said to the British, ‘You can stay and fight, we’re going to blow you out of the water, or you can leave.’ And they left from Dorchester Bay. The bottom line is we've been free ever since. So, it has a unique connection.”

Items on display include Paul Revere’s invoice for a series of rides from May 1775 and a copper plate that he engraved of the occupation of Boston in 1768.

Museumgoers can also see a drum used at the Battle of Bunker Hill, the sword of Major John Buttrick, the officer who gave the order to fire on the British at Concord Bridge, and documents from the Boston Massacre trial.

The exhibit will run through June 17, Bunker Hill Day. The museum is open Monday through Friday, 9 a.m. to 5 p.m. Admissions and parking are free.

“Our export of the world has been democracy,” said Galvin. “Democracy is threatened still to this day, everywhere, including here. What you have here is the evidence of the willingness of those patriots to commit their lives to the pursuit of freedom and democracy and the question is what are we going to do.”