Dennis Banks, one of the country's most influential American Indian activists, was a key figure in the 1970s standoff with federal agents at Wounded Knee. The American Indian Movement he helped found drew attention with a string of high-profile occupations.

But some who worked closely with Banks saw him more as a thoughtful intellectual than a strident fighter. Away from the media spotlight, he worked to preserve American Indian culture, promote wellness on Indian reservations and export traditional products such as wild rice to markets as far-flung as Japan.

Banks died Sunday at the Mayo Clinic in Rochester from complications following open-heart surgery, his family said. He was 80.

"Someone who has such courage as Dennis Banks was everything to us," said Winona LaDuke, the prominent American Indian advocate who considers Banks a major inspiration. "He was a leader in our community, not just to talk but to be there for the community."

In a moving post on Banks' Facebook page signed by his children and grandchildren, his family said Banks "started his journey to the spirit world" just after 10 p.m. Sunday. His children sang traditional songs and prayed over him as he took his last breaths. He had developed pneumonia after surgery 10 days earlier.

"We felt like he was improving, but the pneumonia came on real fast," Tashina Banks, one of Banks' 20 children, said as she traveled Monday afternoon in a family caravan with her father's body from Rochester to a funeral home in Buffalo.

The family said Banks will be buried Saturday in his home community of Leech Lake in northern Minnesota.

Banks, or "Nowa Cumig" in his native language, was born April 12, 1937, on the Leech Lake Indian Reservation. At age 5, he was placed at a boarding school in southwestern Minnesota. At 17, he joined the military and served in Japan.

In 1968, Banks was among the founders of the American Indian Movement in Minneapolis, which started out as a protest against police treatment of American Indians in south Minneapolis and spread nationwide. Under Banks' leadership, marches and takeovers became AIM's signature tactics.

Banks participated in the 1969 occupation of Alcatraz, the San Francisco Bay Area island that had housed a federal prison. In November 1972, he led AIM in a takeover of the federal Bureau of Indian Affairs building in the nation's capital, a protest dubbed "The Trail of Broken Treaties."

Laura Waterman Wittstock, then a reporter for the American Indian Press Association in Washington, D.C., said AIM's grass roots organizing riveted the Washington press corps. In Banks, the movement had a thoughtful spokesman.

"I was impressed with his intelligence and his ability to articulate clearly what he was doing," she said.

Banks and other AIM members made their biggest mark in 1973, when federal agents clashed with hundreds of protesters occupying Wounded Knee in southwestern South Dakota, the site of an 1890 massacre of Indians by federal troops.

Protesters and federal authorities were locked in a standoff for 71 days. Two tribal members were killed and a federal agent seriously wounded. Banks and fellow AIM activist Russell Means were charged in 1974 for their roles in the uprising.

After a trial in federal court in St. Paul that lasted several months, a judge threw out the charges on grounds of government misconduct.

Bill Means, Russell Means' brother, said the two activists helped craft their defense with their lawyers. They used the courtroom and regular news conferences to launch an indictment of the federal authorities' tactics.

"What we did in the 1960s and early 1970s was raise the consciousness of white America that this government has a responsibility to Indian people," Banks once said.

Banks' refusal to shun confrontation made him a divisive figure both in the mainstream and among some reservation officials, recalled Jim Parsons, a retired Star Tribune reporter who covered Banks ­extensively.

"He was being a militant, disturbing the status quo," Parsons said. "AIM was controversial even on the reservation because they were challenging the power of the local tribal chiefs."

Banks spent 18 months in prison in the 1980s after being convicted of rioting and assault for a protest in Custer, S.D., earlier in 1973. He avoided prosecution for several years because California Gov. Jerry Brown refused to extradite him, and the Onondaga Nation in New York gave him sanctuary.

LaDuke said following media coverage of the Wounded Knee trial was a formative experience; as an 18-year-old Harvard University student five years later, she joined AIM and worked for the organization. Banks eventually became a close friend. She said she will remember his humor and kindness, and a joyful dance they shared at a traditional ceremony in northern Wisconsin several years ago.

"He was probably badass, as they say, but I didn't really see that side of him," she said.

Although Banks kept a lower profile in recent years, friends say he remained active in advocacy until his death. In 2010, Banks joined other Ojibwe from the Leech Lake and White Earth bands who tested their 1855 treaty rights by setting out nets illegally on Lake Bemidji a day before Minnesota's fishing season opener.

LaDuke said Banks, who launched a successful wild rice and maple syrup business, pitched in to oppose the genetic engineering of wild rice. To nurture pride in native traditions, he started canoe races on the Mississippi, securing a trip to Japan as a prize. LaDuke ran into him at the Dakota Access pipeline protests in western North Dakota last year.

He also organized caravans that stopped at Indian reservations across the country to raise awareness about various issues, most recently the unsolved murders and assaults of native women.

"Dennis was one of the greatest defenders of Indian rights and human rights of this generation" said Means.

Services in various locations around the state begin Wednesday, with a wake at noon at the American Indian Center, 1530 E. Franklin Av., in Minneapolis. Another wake will be held Thursday and Friday at Banks' home near Federal Dam.

A traditional burial will be Saturday at Bug-O-Nay-Ge-Shig Cemetery at Battle Point on the Leech Lake Reservation. The time for that rite is also pending.

The Associated Press contributed to this report. • 612-673-4482 • 612-673-4781