Elouise Cobell, a Blackfeet tribal member whose fifteen year fight to force the U.S. to account for more than a century of mismanaged Indian land royalties worth $3.4 billion – died late Sunday. She was 65.

Cobell died at a hospital in Great Falls, Montana from complications with cancer, a family spokesperson told the Associated Press.

Cobell was the lead plaintiff in a lawsuit filed in 1996 claiming the Interior Department had misspent, lost or stolen billions of dollars meant for Native American land trust account holders dating back to the 1880s. In the video to the right, Cobell says the class-action lawsuit she filed is the largest in the history of the United States.

Her fifteen year fight led to a $3.4 billion settlement in 2010 from the Obama administration. Cobell funded the class action herself from a $300,000 MacArthur Foundation “genius grant” that she won in 1997.

“Maybe one of these days, they won’t even think about me. They’ll just keep going and say, ‘This is because I did it,’” Cobell said in an interview with the AP. “I never started this case with any intentions of being a hero. I just wanted this case to give justice to people that didn’t have it.”