Mary Dann, who fought the U.S. government to reclaim 24 million acres she considered Western Shoshone Nation ancestral land and became a heroine to Native Americans, has died. Dann, who never gave her actual age, was believed to be in her 80s.

The activist died Friday night of injuries sustained in an accident on an all-terrain vehicle at her Crescent Valley, Nev., ranch. She had been mending a fence.

Dann and her more outspoken younger sister Carrie attracted international attention with their three-decade battle against the Bureau of Land Management.

Their larger issue was whether Western Shoshones could reclaim a vast tract of desert and mountains that extended from the Snake River in Idaho to the Great Salt Lake in Utah across most of Nevada and into California's Death Valley.

The smaller issue, which reinvigorated the legal and congressional property rights debate, concerned whether the sisters could graze cattle on federal land without paying fees.

Dann's sister, the acknowledged spokeswoman of the two, told Associated Press on Saturday that Mary Dann's death would not interrupt their long crusade.

"This was Mary's lifework," she said. "As far as we're concerned, we will live up to our spiritual beliefs and nothing will change that. Mary believed that and lived by it and so do I."

That belief system centered on Western Shoshone ownership of lands that their ancestors had roamed unfettered, living off the land, for eons.

The sisters managed an 800-acre ranch that their parents had acquired through homesteading and purchases from the railroad.

But they also grazed cattle and horses on surrounding federal acreage for which others had paid grazing fees and they had not.

Their fight began in 1973 when Mary Dann, who was herding cattle on horseback, was stopped by a federal agent who said the animals were trespassing.

"I told him he was wrong," she told The Times in 1985. "The land was ours because the Western Shoshone have been here since time began."

The sisters were sued for trespassing. The Western Shoshone Defense Project, which was organized a few years earlier to work on the land dispute, joined the Danns' cause.

At the core of both the big and small issues was the 1863 Treaty of Ruby Valley, which was signed by Shoshone chiefs and ratified by the U.S. Senate.

The treaty allowed white settlers to cross Indian lands, hunt, mine, cut timber, as well as run railroads and establish towns. But it said nothing about transferring ownership of the land to the U.S. government.

In 1946, Congress established the Indian Claims Commission to compensate Indians for lands that had been taken during the westward march.

After some Shoshones submitted a claim, the commission concluded in 1962 that Shoshone land had been lost to whites in 1872 by the gradual encroachment of white settlers.

Payment for the claimed acreage was authorized at 15 cents per acre as the appropriate 1872 value of the land, before the onset of gold and silver mining across Nevada. About $26 million was placed in a trust account in 1979.

The Danns and other activists subsequently won a court round from the San Francisco-based 9th Circuit Court of Appeal, which said that no act of Congress or treaty had ever transferred the land from the Shoshones to the federal government.

But in 1985, the U.S. Supreme Court held on appeal that any Shoshone land rights had been extinguished by placement of the $26-million payment into a trust fund for disbursement.

With interest, the payment had grown to more than $145 million by the time President George W. Bush signed the Western Shoshone Distribution Act on July 7, 2004.

But the Danns and other tribal traditionalists have refused to accept their share of the money, saying that to do so would endanger legal claims to their ancestral land.

Undaunted by the Supreme Court ruling, the Danns continued to graze cattle and horses on federal land despite Bureau of Land Management threats and sporadic animal roundups. After the sisters refused to pay more than $3 million that had been assessed in past grazing fees, penalties and interest, the government seized most of their livestock in 2003 and sold the animals at auction as partial payment.

The Danns considered the dispute ongoing.

In recent years, their fight earned support from human rights commissions of the United Nations and the Organization of American States and from Amnesty International.

In 1993, they received the international Right Livelihood Award from the Stockholm-based Right Livelihood Foundation for "their courage in asserting the rights of indigenous people to their land."

Dann was reared on the ranch, along with sister Carrie and five other siblings. Like her ancestors, she gathered herbs and pine nuts and fished and hunted, as well as tended a garden and herded cattle �?creating a self-sufficient enclave.

Her niece, Patricia Paul, told Associated Press on Saturday that her aunt "died as she would have wanted �?with her boots on and hay in her pocket."