All Portsmouth set out to do was dig a manhole on a two-lane street of clapboard homes. Then a city backhoe hit a slat of white pine in the russet mud. It was a coffin, soft, brown, and six-sided, the first remnant of a buried chapter in New England history. About 200 coffins lay under the street near Choozy Shooz and the other shops that lend downtown Portsmouth a cosmopolitan air. No one knew much about this burial ground because the coffins held slaves, their unmarked graves paved over and mostly forgotten to make way for homes.

PORTSMOUTH, N.H. All Portsmouth set out to do was dig a manhole on a two-lane street of clapboard homes. Then a city backhoe hit a slat of white pine in the russet mud. It was a coffin, soft, brown, and six-sided, the first remnant of a buried chapter in New England history.

About 200 coffins lay under the street near Choozy Shooz and the other shops that lend downtown Portsmouth a cosmopolitan air. No one knew much about this burial ground because the coffins held slaves, their unmarked graves paved over and mostly forgotten to make way for homes.

Captured on West Africa's coast 300 years ago, slaves were used as rope-makers, shipwrights, potters, and cooks. Some were owned by the city's founders: William Whipple, a Revolutionary War commander who had a street and school named for him, kept a slave.

Now, as the remains of eight slaves are stored in a locked public works building, this city that prides itself on progressivism is confronting its past.

Several black residents have submitted DNA to determine if the remains are their ancestors, the city has voted to build a memorial, and officials are planning a proper funeral for the eight.

For many, a memorial is a matter of pride. With a black population of about 500, Portsmouth has, per capita, the largest black population in New Hampshire.

Maps made by the Portsmouth Black Heritage Trail show docks where black mariners worked in the 1700s, and a church where residents raised money for civil rights in the 1960s.

"It was ignored and just kind of brushed aside as unimportant," said David Sawyer, 56, a dishwasher at Bob's Broiled Chicken, who has followed the burial ground's discovery in the local paper. "They're trying to correct that and give them a proper place in Portsmouth's history."

Portsmouth, 60 miles north of Boston, considers itself harmonious and industrious. Slavery has never fit easily into that picture.

The website for Strawberry Banke Museum, a local tourist destination, said, "This has always been an ordinary neighborhood, inhabited by ordinary people."

The first documented slaves arrived here in 1645, some 22 years after the first settlers, said Valerie Cunningham, president of the Portsmouth Black Heritage Trail who has studied black history in the region for decades.

By the mid-1700s, the city had about 200 slaves, roughly 4 percent of its population. About 656 slaves lived in New Hampshire, few compared with the 5,000 in Massachusetts, 3,700 in Rhode Island, and 6,400 in Connecticut...

...Portsmouth's slaves built ships that brought more slaves to the colonies.

Others worked as seamstresses and gardeners, according to Cunningham. Some pressed for the right to farm or travel freely.

When they died, they were buried separately from whites. Some were buried on their owners' land, but many were sent to a plot at what was then the edge of Portsmouth: "The Negro Burying Ground," on Prison Lane, it was called in 18th-century records.

As Portsmouth grew in the 1790s, residents built over the burying ground, erecting houses.

The only records of the burial ground are a few 18th-century maps and a 19th-century newspaper article about another road crew hitting coffins there.

Then on the morning of Oct. 7, 2003, a road crew hit another coffin and someone yelled, "Stop!"...

...Examining bones, archeologists determined that four of the exhumed remains were of men in their 20s, and one was of a woman of about 30.

DNA tests showed they were of African descent, and the woman also bore a telltale cultural marker: Her incisors had been removed, typical of a West African coming-of-age ritual.

Beyond that, archeologists believe there is little hope of learning more about the slaves...

...In 2004, Mayor Evelyn Sirrell named a teacher, lawyer, city councilor, and historians to a Blue Ribbon African Burial Ground Committee to decide the fate of the graveyard.

Last year, after hearing from archeologists and high school students, they recommended closing part of Chestnut Street, where the graveyard is located, and planting a grassy memorial for an estimated $100,000.

The City Council accepted the plan, voting unanimously.

Residents are planning a funeral, with some anticipation.

"We want quite honestly to make amends for the way it had been done then," said John W. Hynes, a city councilor and chairman of the Burial Ground Committee. "We are trying to do justice."