WORTHINGTON, Minn. (AP) – The largest mass execution in U.S. history occurred 148 years ago, when 38 Dakota warriors were hanged from a single scaffold in Mankato.

The shock waves of that mass execution still reverberate today among the Dakota people. A new documentary film remembers the 38, and also a group of Dakota who ride on horseback each year at this time to Mankato to commemorate the executions of Dec. 26, 1862.

The U.S.-Dakota War played out along several all-too-familiar themes of U.S. history: broken treaties and unfulfilled promises. The war started in August of 1862 and when it was over six weeks later, hundreds of Indians, settlers and soldiers were dead along the Minnesota River valley.

Filmmaker Silas Hagerty said his introduction to the war came five years ago. At a traditional sweat lodge ceremony, an Indian spiritual leader told Haggerty about his dream – a dream of a journey.

“Riding on horseback across South Dakota and Minnesota, and arriving on the bank of a river in Minnesota, which he later discovered was Mankato,” Hagerty said. “And in his dream he saw these 38 Dakota warriors, all hanged at the same time.”

The dream inspired an annual horseback ride from the Missouri River in South Dakota to Mankato to remember those executed. That journey, in turn, inspired Hagerty and his colleagues to honor both the modern-day riders and those hanged in 1862.

“We want to distribute the film as a gift,” he said.

Dakota 38 documents the ride to Mankato in 2008. It was a memorable trek, filled with blizzards but also warm greetings from small-town residents along the way. In the movie, Indian spiritual leader Jim Miller describes his painful dream and its hold on him.

“I tried to put it out of my mind,” Miller said. “But it was one of them dreams that bothers you night and day.”

That moment captures the spiritual burden of the 1862 war for the Dakota. It’s a burden that dominates the film.

The conflict began over broken promises of food and other goods that the United States government made the Dakota in exchange for land. The fighting included battles at Fort Ridgely and New Ulm.

When it was over, hundreds of Dakota fighters were arrested and sentenced to death, charged mainly with killing civilians. After pleas from Bishop Henry Whipple and others urging leniency, President Abraham Lincoln spared most of the accused, except for the 38 eventually hanged.

The Dakota were evicted from Minnesota, sent to live on reservations in Nebraska and the Dakotas. Some ended up as far away as Canada. Hagerty said those events left scars.

“There’s a lot of historical trauma and it’s talked about in the film,” he said. “Where a lot of the Dakota men on the ride speak of this genetic depression that’s passed from one generation to the next.”

The problems are evident in alcohol and drug addiction, suicides and family breakdowns among Native Americans. The film confronts the viewer with the damage those issues cause.

At the end of Dakota 38, the filmmakers reveal that one of the young men featured in the film recently committed suicide.

Dakota 38 co-director Sarah Weston, a member of the Flandreau Santee Sioux Tribe, said the suicide is part of what she calls the `historical grief’ left over from the traumatic collision in the 1800’s between Native Americans and white settlers.

One of the film’s messages, Weston said, is that the Dakota and other Indians should take a simple but difficult step: Forgive the misdeeds of the past.

“The past is really, really traumatic,” Weston said. “But we’re going to reach our hand out and say that we forgive. Because when you’re not in a forgiveness place, you’re linked to that person or that trauma for the rest of your life, all day long. And so by forgiving we’re no longer linked to that.”

Weston and her colleagues hope the film will be finished and released next year. Right now they have a rough cut in hand, and they’ve been previewing it at several locations throughout the region, including along the route of this year’s ride to Mankato.

Minnesota Public Radio News,