John Heisick conjures up childhood memories when he gazes out his patio door and sees the engraved granite slab, a reminder of a tragic episode that transpired near Upsala, Minn., more than 150 years ago.

"I was living here with my grandparents when I was born in 1942 because my father was in the war," Heisick said. "On the back side of the house, there was a play area for me with three lilac bushes."

Those lilacs are gone now, but Heisick remembers his grandmother Minnie Heisick telling him the bittersweet backstory. They were planted over the graves of two children who died in 1870. The bushes were pulled out when a new home replaced the old farmhouse in 1957.

Ten-year-old Maria Peterson and her 8-year-old brother, Christian, the children of Dutch immigrants, had ventured out to bring in the family cows when they became lost in the woods in October 1870. More than 100 men searched for two weeks through poplar brush, scouring sloughs, marshes and swamps, but with no luck.

"They had disappeared so completely as if some gigantic bird of prey had swooped down and carried them away," Nate Dally, then a 22-year-old settler in the area, wrote in his 1931 memoir "Tracks and Trails."

Two months later, a Native American hunter found Maria's fresh footprints in the snow and followed them until he came across her body in a makeshift shelter along North Two River "emaciated almost beyond description," according to Dally wrote.

Maria was thought to have died within 24 hours of her discovery by the hunter, based on the tracks in new snow. As settlers prepared to transport her remains, one of their dogs scratched at the nearby snow and unearthed Christian's frozen body. He appeared to have been dead for a month.

"People wonder why they didn't follow the river, but they might have followed it the wrong way," Heisick, a retired factory worker who lives at the farm, said during a recent phone call.

In his memoir, Dally theorized that Christian became so ill or exhausted that he could go no further, and that Maria "would not desert" her younger brother. He defended their parents, Andreas and Theodosia Peterson, against those who blamed them for sending children into the wilderness.

"That was a common way of doing things in those days," Dally wrote, recalling how he and his brothers also would occasionally get lost searching for cows.

Their story easily could have been lost to history if not for three people: Dally, who wrote about his firsthand memories 61 years later; Dan Hovland, a special education teacher who dug into the records as president of the Upsala Area Historical Society, and Heisick, who was haunted for years by the story his grandmother told him.

No one even knew the lost children's names until Hovland, now 74 and living in Willmar, had an a-ha moment while doing research at the Morrison County Courthouse in Little Falls in the 1990s.

Sifting through paperwork there, he found death records for Maria and Christian Peterson. Their date of death is recorded as Oct. 31, 1870, and the cause was handwritten: "Lost in the woods."

The Petersons' daughter Mary sold the family farm three miles east of Upsala — about 35 miles northwest of St. Cloud — to Heisick's grandfather in 1920.

In 2006, Hovland joined Heisick and his wife, Ruth, in dedicating the memorial stone to the Peterson children in their yard — relying on Heisick's memory of where the lilac bushes once grew to pinpoint the spot where they were buried. The stone is inscribed "The Lost Children of Two Rivers."

"We used the old stone foundation from the original house and went straight east about 12 feet and I'm sure we're within five feet," Heisick told me. "I always thought there should be a marker. Thirty years ago, people my parents' age all knew the story. But the residents have changed and the others who've come in know nothing about the children disappearing."

"The old house and the lilacs are gone. In years to come, nobody would have remembered them."

There's an old cautionary poem called "Two Babes in the Woods," which was often recited to children. "My dears, do you know how a long time ago / Two poor little babes whose names I don't know / Were stolen away on a bright summer day / And left in the woods, so I've heard people say / ... / They sobbed and they sighed and they bitterly cried / And the poor little things, they lay down and died / ..."

The song has many versions and may date back centuries, but it's often associated with Maria and Christian. It ends with the lines: "And when they were dead, the robins so red / Brought strawberry leaves and over them spread / And all the day long, they sang them this song: / Poor babes in the woods, poor babes in the woods! / And don' you remember the babes in the woods?"

Hovland spread strawberry leaves as he read the poem at the 2006 memorial dedication to the children, its words carved in the granite slab.

Curt Brown's tales about Minnesota's history appear every other Sunday. Readers can send him ideas and suggestions at mnhistory@startribune.com. His latest book looks at 1918 Minnesota, when flu, war and fires converged: strib.mn/MN1918.