HARPERS FERRY, W.Va. — It was last summer that Bonnie Zampino first noticed something unusual about the wooded plot of land in the hills above this historical town.

Zampino, a case manager for recovering drug users who lives in the neighboring community of Bolivar, was used to encountering curiosities from the past on her hikes through Harpers Ferry, a town where history has left its imprint several times over. The village overlooking the Shenandoah and Potomac rivers is most famous for the failed anti-slavery raid led by abolitionist John Brown in 1859. It was also the site of a Civil War battle and hosted large contingents of Union and Confederate troops.

Zampino, 50, had made a hobby of her interest in abandoned rural properties, taking photographs and researching old land records. But the lonely section of woods to the west of Harpers Ferry’s historical downtown and national park were unlike anything she’d seen before. Thin, jagged slabs of stone stuck up in rows. There were bathtub-size depressions in the ground — what Zampino would later learn can be a sign of settling graves. A small, white footstone sat unsteadily in the earth, like a loose tooth.

She set out to learn more about the town-owned property. Records were scarce, but after months of archival sleuthing, Zampino developed a theory that this section of woods is a forgotten remnant of some of the nation’s darkest and bloodiest days. She thinks she has discovered a lost graveyard of Union dead.

Her hypothesis, at this point, is only that. Even if soldiers’ remains are buried at the site, the number of bodies is uncertain. Zampino’s detective work has been complicated by confusing and sometimes contradictory records from the years immediately after the Civil War, a time when many of the corpses left behind by America’s deadliest conflict were disinterred and — at least in the case of federal troops — moved to special resting places.

But Zampino has uncovered compelling documentary support for further investigation, including National Park Service and military records — some dating back 150 years — that point to a soldiers’ cemetery at the location in question and suggest it fell into neglect not long after the war ended.

“Whoever’s here, I’d like to know,” she said, standing at the site in Harpers Ferry on a recent afternoon. A narrow lane of cracked pavement runs through what Zampino believes to be the old cemetery. The ground was covered in matted leaves and fallen branches. “This shouldn’t look like this,” she said.

The roots of the mystery Zampino has been trying to solve lie in a largely forgotten epilogue to the Civil War. The American military has long prided itself on the faithfulness with which it recovers the remains of those who die in conflict. After the war’s end in 1865, that endeavor took place on a huge scale, with federal officials fanning out to battlefields to retrieve the bodies of soldiers, sometimes in advanced states of decomposition. Those remains were reburied in new national cemeteries.

The job, while harrowing, was deemed essential by the government and welcomed by relatives of the fallen.

“Words fail to describe the grateful relief that this work has brought to many a sorrowing household,” wrote David Wills, a lawyer who led the effort to create the Gettysburg National Cemetery.

John Frye, a local historian and curator of the Western Maryland Room at the Washington County Free Library in Hagerstown, Md., said it was unlikely that the federal government could have overlooked a sizable number of bodies in Harpers Ferry during its retrieval efforts. Zampino said she believes anywhere from dozens to several hundred soldiers may have been interred at the site based on records she has reviewed.

“I can’t imagine the United States of America letting 300-some graves of Union soldiers go unmarked,” Frye said in an interview.

Zampino has gotten used to skepticism — or plain confusion: At the outset of her research project last year, most people seemed unaware that bodies had ever been buried at the site she discovered. “The more I couldn’t get information, the more I was like, ‘Man, I want to figure this out,’” she recalled.

She eventually discovered a 1959 National Park Service report that identified the plot as Pine Grove Cemetery, established in or around 1852. The report stated that “the cemetery was used as a burial ground during the Civil War.”

At the National Archives, Zampino discovered letters between military officials from 1866 to 1869 that discuss a “Citizens Cemetery” — separate from the other known cemeteries in Harpers Ferry — that she believes to be Pine Grove. An 1866 quartermaster general’s report says the cemetery “contains a number of soldiers graves, said to be not less than 75” that are “not distinguishable from citizens graves.”

Even then, however, confusion reigned over what the graveyard held.

In 1867, a military officer, responding to a request that the cemetery walls be rebuilt to protect the commingled grave plots of soldiers and civilians, replied that “all the bodies of U.S. soldiers interred at Harpers Ferry” had already been moved to Winchester National Cemetery in Virginia. Military records of the war dead from the time state that hundreds of soldiers’ bodies were moved from Harpers Ferry to Winchester between 1866 and 1867, but they are vague about what cemetery they came from. Zampino said they might have come from the more famous and centrally located Harper Cemetery.

At this point, Zampino said, the only way to resolve the questions raised by the documents is to conduct a physical examination of the site for graves and human remains. To that end, she is hoping to work with the Harpers Ferry Historic Landmarks Commission to apply for a grant that would fund ground-penetrating radar.

“I think it’s worth pursuing,” said Deborah McGee, the commission’s chairwoman.

If such research confirms the presence of soldiers’ remains, the National Cemetery Administration said, it “stands ready to provide government-furnished markers and/or grave space in a national cemetery.”

Whatever the outcome, Zampino said, she believes that after a century and a half, it’s time to solve the mystery of who rests in Pine Grove cemetery.

“There are people here,” she said. “And nobody knows who they are.”

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