On a gently sloping hillside studded with pine trees, clues to a Revolutionary War mystery are slowly being revealed, spurred by the dogged efforts of a local historian and his teenage son. An archaeological survey last week conducted on an unspoiled swath of land about 15 miles west of Newark Liberty International Airport produced several dozen items including metal buckles, a knob from a desk drawer, a shard from a clay pot and a partial pipe bowl. William Styple, an author and editor of numerous American history books, believes those artifacts are proof that Gen. George Washington’s army made camp there for several months in the winter of 1777, a year before the ragtag group hunkered down at its more well-known refuge at Valley Forge, Pennsylvania. “We know they ate here, we know they smoked here, we know they unstrapped their gear here,” he said. If Styple is right, it could add a chapter to the historical record of the Revolutionary War that has been hinted at but never fully explored. Compared with Valley Forge, considerably less is known about the 1777 encampment, which closely followed Washington’s famous crossing of the Delaware River and the battles of Princeton and Trenton. That there is virtually no contemporaneous written record of the camp casts some uncertainty over the site’s location, however, said Eric Olsen, park ranger and historian at nearby Morristown National Historical Park, site of Washington’s army’s camp in the winter of 1780. “It could be an encampment during the war, possibly ’77,” Olsen said. “But armies constantly marched through here through the entire American Revolution, and bits of armies were camping as they passed through.” It was Styple’s research over the last year, with a key assist from his son, that led him to the largely pristine land that had been used as farmland before it became part of the Geraldine Rockefeller Dodge estate for much of the 20th century. Fortuitously, and unbeknownst to Styple at the time, Chatham officials had completed the purchase of the land late in 2014 and earmarked it for open space. Styple had come across an 1855 newspaper article that reprinted a speech by the Rev. Samuel Tuttle, who allegedly interviewed people who were old enough to have witnessed the camp. On a visit to a library in Morristown, Brad Styple, a high school junior who shares his father’s keen interest in history, located two photographs from 1890 that showed a mansion that stands on the same spot today. A marking on one of the photos was described as the location where the camp’s flagpole flew the Grand Union, the forerunner to the Stars and Stripes. “It is really cool to be able to find your own piece of history,” Brad Styple said last week. The newspaper article described the first troops arriving in early January 1777. For the next several months they ate, slept, performed daily drills, got drunk on whiskey from local peddlers and did their best to stave off the winter’s cold. It was a harsh existence: Many soldiers died from smallpox, and some deserters were punished by hanging or by running a gauntlet manned by soldiers wielding whips cut from nearby trees, according to Tuttle.