FAIRFIELD — On Jan. 7, 1765, in the middle of the Stamp Act controversy, Boston shopkeeper Harbottle Dorr bought an issue of the Boston Evening-Post and commented on its contents in the margins.

Every week for the next 12 years, he did the exact same thing.

The result is 3,280 pages of newspapers-turned-diaries that give an unprecedented look at the American Revolution as it happened, by someone in the center of it.

On Aug. 25, those newspapers — possibly worth hundreds of thousands of dollars — will be auctioned at James D. Julia Auction House, in a sale that’s attracting national attention.

“I was startled when I saw they were for sale,” said Stephen Hanly, owner of Bickerstaff’s Books, Maps, Etc. in Scarborough, which specializes in printed materials from 18th century New England. “They are more than newspapers, clearly, because Harbottle Dorr turned them into a narrative on the American Revolution. They are a rare and significant piece of Americana.”

Most notably, Dorr’s newspapers include a July 18, 1776, copy of the Boston Gazette, which reprinted the entire Declaration of Independence on its front page. It’s one of only a dozen or so known contemporary reprintings of the Declaration still in existence.

In 2007, a similar reprinting from the Pennsylvania Evening-Post sold at auction for $360,000 — and that wasn’t part of a massive, well-preserved collection.

Although the newspapers have little to do with Maine, the Bangor Historical Society has owned them for nearly 100 years. In 1914, a Bangor resident shopping for antiques in Massachusetts bought the collection and donated them to the society.

But with the society on the verge of shuttering because of lack of money, its board made the painful decision earlier this year to sell the newspapers.

“The economy has been very difficult,” said Dana Lippitt, the society’s curator and only remaining full-time employee. “It’s kind of a sacrifice, but it’s something we’ve got to do.”

Although the Bangor Historical Society has about 40,000 items in its collection, few pieces have the value of the Dorr newspapers, which span 1765 through 1777. That’s one reason the society chose to sell them. The money will likely help keep the 147-year-old organization open, Lippitt said.

But the newspapers also have little to do with the society’s core mission of preserving and retelling Bangor’s history, she said. Furthermore, the society can’t afford the kind of storage that would best preserve the collection.

Timothy Hughes, owner of Timothy Hughes Rare & Early Newspapers, said he hopes an institution, not a private dealer, ends up winning the auction. With 2.5 million rare newspapers in his Pennsylvania warehouse, Hughes is the largest dealer of historical newspapers in the country.

“Dealers have a tendency to break collections up and sell pieces individually,” Hughes said. “And it would be a shame if such a collection was broken up. That would be like ripping out the pages of a great book.”

The newspapers being sold are only one-fourth of Dorr’s collection. The Massachusetts Historical Society has the other three-fourths.

Lippitt said the Bangor Historical Society’s board considered a private sale to the Massachusetts Historical Society to complete its collection. “That’s where we’d prefer they end up,” Lippitt said. But the need for the most money possible convinced board members to put the newspapers up for auction.

In addition to the Massachusetts Historical Society, likely suitors for the collection include the Library of Congress, the American Antiquarian Society in Worcester, Mass., and the William L. Clements Library at the University of Michigan — all of which have a keen interest in early American history.

According to Seth Kaller, a historical documents expert based in New York, 29 newspapers printed the full text of the Declaration of Independence by the end of August 1776.

But few copies from any of those have survived, Hanly said, because until the last few decades, few people took an interest in preserving newspapers.

“How many are still buried in attics, we don’t know,” Hanly said. “But the survivability of individual issues is fairly limited, and there’s even fewer with annotations like Harbottle Dorr’s. That makes them even more unique.”

Hanly said despite the bad economy, the top-level auctions haven’t seen much of a dip in prices.

Hughes said he wouldn’t be surprised to see the winning bid top $200,000.

“There’s not a lot of comparable sales,” Hughes said. “Dorr collected these himself in the 1700s, which few or no others did. To have a collection like this is not typical at all, but that only makes the sale more interesting and exciting.”