Back in the 1960s as a young teen, Sue Wall of Portland peeked into an old metal box and was struck by its contents. A tarnished bugle, handwritten letters, photographs, diaries and other artifacts belonging to her great-great-grandfather, a German immigrant and Civil War soldier, seemed to have originated from another world.

Frederick Miller of Company K of the 1st Ohio Light Artillery was born in Bavaria and joined the U.S. Army as a bugler at the tender age of 18. He didn’t become a U.S. citizen until 1882, after the cannons of war had long quieted.

Wall’s sister, Becky Hyde Gowdy, has Miller’s cavalry sword. One item in the box, the diary, proved especially intriguing. It was written in code. Some of it was in German. The semantics were eventually cracked and the sisters were pleasantly surprised at what was revealed. Instead of military secrets, the words took the form of a love-letter. This and other artifacts will be displayed and discussed at the Windham Historical Society on Saturday.

The program is titled “Sounding the Battle Cry of Freedom: True Stories of the Civil War,” which is one of several events in the society’s five-year commemoration of the war that nearly cleaved a nation. Next month, the society will offer a Power Point presentation on the story of the former Gambo Gunpowder Mills of Gorham and Windham, which supplied one-quarter of the gunpowder used by the Union Army. A tour of the mill site’s ruins is also planned.

Windham Historical will host an encampment of Company A, 3rd Maine, with demonstrations on the weekend of June 23-24. Special exhibits on the Civil War era will be on display inside the society’s museum.

In the mid-to-late 70s, Wall was studying history in college and used her family’s artifacts as part of her coursework.

“Some of the letters were in German,” Wall said. “I had a German professor transcribe them. She was familiar with the old script. It was very difficult for her, but she did a great job.”

The diaries and letters were amazingly detailed, including weather conditions and what batteries marched on what towns.

After Wall completed college, the material lay dormant for many years. Wall lived in Florida for a time. When she returned to Maine almost a decade ago, she joined the Cumberland Historical Society. She credits society president Carolyn Small with reviving her interest in the material.

“Carolyn suggested I should be on the program committee and that I should do a program,” Wall said. “I had this history paper I had written in 1978 and these artifacts, so I based a program around that.”

Since then Wall and Gowdy have put together a five-part program centered on the Civil War that includes not only Fred Miller, but another Union soldier, their other great-great-grandfather, Andrew Young.

Young was from Dover, N.H. Miller was from Ohio.

“That’s where our story begins,” Gowdy says, “with Miller’s family migrating to Ohio. It’s great fun reliving what it must’ve been like. The letters come alive.”

On Saturday, the sisters will present the first two parts of their program: “Bugle Boy of Company K: Fred Miller in the Civil War” and “Home Life during the Civil War.”

The sisters have learned a lot from examining the material. It was a different time in our nation’s past. The conflict claimed some 600,000 men — 2 percent of the population died — more than any American war before or since. However, the sisters discovered some things have not changed.

“One key thing we’ve learned,” Gowdy said, “is that family relationships from 1860 are not unlike family relationships of today. They are remarkably similar. There’s tragedy and love, unhappy marriages. It’s quite remarkable how human these letters are and that we can relate to them 150 years later.”

The free program begins at 9 a.m. Saturday at the Windham Public Library, 217 Windham Center Road. Donations are welcome. Refreshments will be served.