Archaeologists have discovered the site in southeastern Alaska where an indigenous tribe built a wooden fortress more than two centuries ago to withstand Russian invaders.

The fort was built in the early 19th century by the Tlingit in Sitka on Baranof Island, which is part of what is now the Alaska Panhandle, to defend themselves against Russian invaders in the Battle of 1804, according to the National Park Service website. The Sitka National Historical Park was created to protect the battlefield, according to the Park Service.

“It’s a pivotal historic event in the history of the area, but it’s now an important symbol for the people of Tlingit in our time,” said Thomas Urban, a researcher at Cornell University and author of a study published Monday in the Antiquity magazine detailing the discovery. “It’s a sacred place.”

The exact location of the fort, which was demolished by the Russians shortly after the Russian victory, had long escaped the archaeologists, who had previously only found clues and traces of it.

The large-scale survey, conducted in the fall of 2019 by Mr. Urban and Brinnen Carter, a National Park Service archaeologist, discovered electromagnetic anomalies that revealed the perimeter of the fort and the shape and dimensions of the Russians in the 19th century matched, said Mr. Urban.

“Something is different underground where the fort was,” he said. “It could be that they had a ditch and wood. The soil is compacted differently, so there are some physical properties that differ at the edge of the fort. “

The fortress has long been believed to be in a clearing in the park called the fortress clearing, Urban said. However, the survey found that the fort extended beyond the clearing into the surrounding forest, about 20 feet in each direction, he said. The survey spanned 40 acres, which Urban said should rule out the possibility of an alternative location.

“There is no other place in the park that has such a geophysical signature,” he said.

The Tlingit built the Shís’gi Noow fortress, which means tree fortress in the Tlingit language, at a strategic location at the mouth of the Indian River, adjacent to flat side lines, “to prevent the Russians from bringing their naval artillery near The fort’s walls effectively neutralize its military advantage, ”the Park Service website reads.

The Tlingit had successfully defeated Russian invaders in 1802, which severely affected the fur trade and the Russian stronghold in Alaska.

When the Russians returned in the fall of 1804, the Tlingit were able to repel the attack, but suffered a setback that threatened their survival: a canoe carrying their reserve gunpowder exploded the night before the battle, according to the Park Service website.

Running out of gunpowder, the Tlingit made the tactical decision to leave the fort at night a few days later and move to another island in what is now the Alaska Panhandle, according to the Park Service. The Russians won the battle and occupied Alaska until 1867 when it sold its territory to the United States.

Before dismantling the fort, the Russians made a detailed sketch and recorded the dimensions of the fort, which Mr. Urban said was consistent with what he and Dr. Carter found. The story of the battle was also passed down orally by the Tlingit. (Members of the Sitka tribe of Alaska, whose ancestors fought the Russians, did not return voice messages or emails asking for comments on Tuesday and Wednesday.)

Mr Urban said that finding the location of the fortress would give the Tlingit people a physical place to connect with their history.

“It is part of a living cultural landscape that is important for the people who are there now,” said Urban. “To be able to confirm it as a place and that this story has a physical form – I think that’s very important.”