For nearly two decades, Brian O'Neill fought Exxon after the catastrophic 1989 Exxon Valdez oil spill in Alaska's Prince William Sound.

The charismatic environmental lawyer led the Minneapolis-based legal team at Faegre & Benson that distributed $1 billion to thousands of native Alaskans and fishermen affected by the spill, a crusade chronicled in the book "Cleaning Up" by Minnesota author David Lebedoff. It was a herculean chapter in O'Neill's career. There were many others, including ones on wolves, bald eagles and the Boundary Waters Canoe Area Wilderness (BWCA).

"Brian is the leading lawyer in the last 40 years in making sure that Minnesota's wild places and wildlife are preserved for the future," said Faegre Drinker partner Richard Duncan, O'Neill's longtime colleague.

O'Neill died at his Minnetonka home on May 6 from amyotrophic lateral sclerosis, or ALS. He was 72.

Brian Boru O'Neill was born in Hancock, Mich., the first of six children. His father was a U.S. Army officer, and O'Neill attended schools in Japan and Germany as well as the United States.

After graduating from West Point in 1969, O'Neill served in the Army, graduated from the University of Michigan Law School and went to work at the Pentagon's Army General Counsel Office. According to the book "Cleaning Up," he ended up in Minnesota after a squash partner told him about Faegre & Benson in Minneapolis and urged him to meet with one of its senior lawyers.

O'Neill went on to work at the firm for 34 years, becoming a partner. He worked in Faegre's business litigation group and headed the firm's environmental practice protecting natural resources. His heart's passion, friends and family say, was the pro bono work he did for clients such as Defenders of Wildlife, the Sierra Club and Friends of the Boundary Waters Wilderness.

Duncan said that O'Neill came to prominence in Minnesota in the late 1970s and early 1980s, when he litigated to stop a proposed sport hunting season on wolves in Minnesota.

He also successfully sued the U.S. Environmental Protection Agency to restrict strychnine, which was being used to control rodents but was poisoning bald eagles and other birds. And for years, Duncan said, O'Neill fought legal challenges to the restrictions on motor boats in the BWCA.

"He really believed in the idea of preservation of wild places and wild things, that human beings shouldn't assert domain over everything," Duncan said.

O'Neill's wife, Ruth, said she first met him in 1988 when she applied for an environmental internship at Faegre. But she almost didn't take the job because he was so gruff and "kind of barking orders at people." His true colors showed, she said, when she told him her mother had recently died. He immediately softened. She took the job.

One year later, the Exxon Valdez tanker struck a reef and spilled 11 million gallons of crude oil into Prince William Sound. O'Neill asked her if she wanted to go to Alaska for work. Off they went. "Within three days we were madly in love with each other," Ruth said.

In 1994 — five years after the spill — an Alaska jury ordered Exxon to pay private plaintiffs $287 million in compensatory damages and $5 billion in punitive damages. There were years of appeals, however. The U.S. Supreme Court would slash the punitive damages to $507 million. The final sum rose with accrued interest of nearly $500 million.

Although he was angry with the U.S. Supreme Court decision in the Exxon damages, he did not despair, Ruth said. It wasn't in his nature.

In addition to his wife, O'Neill is survived by children Dru Groves, Brian Severns, Maggie Severns, Phelan O'Neill and Ariel O'Neill and three grandchildren. Services are pending.