Groton — On a clear day, visitors to Fort Griswold Battlefield State Park can view the mouth of the Thames River and grasp the strategic importance of the Revolutionary War-era fort.

Saturday was not a clear day and mist enveloped the area, but it did not deter Groton resident David Rose from explaining to visitors that the fighting that took place here was “clearly the only real battle in the state of Connecticut” during the Revolutionary War.

Rose is a member of the Friends of Fort Griswold, and he donned colonial-era clothing to lead tours of the fort on Saturday as part of the nonprofit group’s fourth annual open house and bonfire.

There was no bonfire because of the weather, but there were dozens of folks in attendance touring the grounds of the park and viewing revolutionary war artifacts in the Monument House Museum.

Rose, who lives around the corner from the park, has been giving tours for years and will often stop when walking his dog to educate visitors on the site’s history.

“It keeps the history of the fort alive and ensures it doesn’t disappear, as things do,” Rose said. “We do this for the community.”

The museum features a model of the fort as it existed during the bloody Battle of Groton Heights on Sept. 6, 1781, when the British landed 800 men on the Groton side of the Thames River. The British soldiers, along with other British forces that landed in New London, were under the command of famous traitor Benedict Arnold.

More than 80 militia members under Colonel William Ledyard died defending Fort Griswold, in what is referred to as a massacre on a plaque mounted on the outside of the 135-foot monument in the park.

The Groton Monument was completed in 1830 “in memory of the brave patriots who fell in the massacre at Fort Griswold, near this spot, on the 6th of Sept. AD 1781 when the British, under the command of the traitor Benedict Arnold, burnt the towns of New London and Groton and spread desolation and woe throughout the region.”

Pauline Godwin and her grandson Gavin, 6, ascended to the top of the monument and its 166 steps on Saturday to catch a glimpse of the area from the top.

While there wasn’t much to see because of the fog, Godwin said her grandson “really loves this historical stuff,” and was captivated by monument and the displays inside the museum. Those displays included muskets and a sword used by a fallen 17-year-old soldier stationed at the fort.

Friends of Fort Griswold had an array of snacks and items for sale in its gift shop. Godwin, after a visit with Saxophone Santa, snagged a rifle-shaped pen for a gift.

Hali Keeler, president of Friends of Fort Griswold, called the museum a “fabulous little treasure” that deserves more attention. The group raises money to help augment the experience at the park — things like an interactive kiosk, interpretive signage and a granite foundation in the barracks in the fort.

Keeler said she was disappointed with the lack of a bonfire but was encouraged by the number of visitors and lack of rain.

Friends of Fort Griswold is now in the planning stages for the 240th Anniversary of the Battle of Groton Heights in two years. There are reenactment groups, skirmishes and encampments planned for the event.

For more information, visit fortgriswold.org.