At age 91, Erna Rosenberg took out her walker and joined a weekly antiwar protest on a Newton Centre corner in 2003. The Bush administration had just declared America’s victory over Iraq.
Sitting in a lawn chair, she held a homemade sign that April day declaring, “Winning doesn’t make it right.”
Bundled up against the springtime chill, the Brooklyn, N.Y., native and self-described “old-time lefty” whose activism was forged during the McCarthy era gave a Globe reporter an earful in an interview.
“We’re in the wrong. We’re pigs, and I’m ashamed for my country,” she said as about 40 protesters denounced the Iraq War, calling it American imperialism that was responsible for an untold number of Iraqi civilian deaths.
Mrs. Rosenberg, a longtime Newton resident and a political firebrand who raised four children, was 100 when she died June 23.
Diagnosed last year with aortic stenosis, she died in her home at Lasell Village, a retirement community affiliated with Lasell College, where she found new purpose in her 90s attending courses in writing and poetry, according to her family.
“She was just very engaging and very interested in things,” said her son Joshua of West Palm Beach, Fla. “She was very well informed, very opinionated, and curious about how others thought and lived.”
Her son John, who lives in Los Angeles, said Mrs. Rosenberg “was really quite an amazing person.”
Mrs. Rosenberg and her late husband, attorney Allan R. Rosenberg, married in 1937 and adopted two boys and two girls.
Embracing her children’s interests, Mrs. Rosenberg became an avid sports fan, thanks to the athletic careers of her sons, they said.
John served as head football coach at Brown University and previously had been an assistant coach at Pennsylvania State University.
“How many lefty, progressive peace activists subscribe to NFL Network in their 90s?” John asked.
Devoted to New England sports, Mrs. Rosenberg was crushed when the New England Patriots lost the Super Bowl this year, and she arranged her schedule around Red Sox games on television.
“She could give you a sports page-worthy editorial on what the Red Sox should or should not have done with Daniel Bard,” John said of the Red Sox player who was a starting pitcher before being sent down to the minor league team in Pawtucket, R.I.
In addition to her sons, Mrs. Rosenberg leaves two daughters, Lucy Segal of West Newton and Amy Green of Hampton Bays, N.Y.; five grandchildren; and a great-grandson.
Segal said Mrs. Rosenberg had a passion for living and for cooking meals from scratch. Each summer, she went berry picking, made pies, and canned her bounty of summer fruits.
“We’d have these fabulous pies for Thanksgiving and throughout the year,” Lucy said.
As a centenarian, Mrs. Rosenberg donated her DNA to scientists competing to win the Archon X Prize for Genomics, a gene sequencing contest involving genes from 100 centenarians.
She told the Archon prize organization that her favorite decade was the 1990s, which she called “the Clinton decade,” and that President Obama was the leader who impressed her the most.
Mrs. Rosenberg also was asked which innovation had the greatest impact on her life.
“My favorite invention is the automobile,” she said in a brief interview posted on the organization’s website, genomics.xprize.org. “The computer is extremely important and is changing the world, but the automobile affected my life more.”
Born Erna Rothchild in Brooklyn on July 26, 1911, she was one of three children born to Louise and David Rothchild. Her father was a diamond merchant.
In New York City, she graduated from Hunter College High School and, in 1932, received a bachelor’s degree from Barnard College. Moving to Washington, D.C., she went to work for a New Deal program known as the Rural Electrification Administration.
Her husband began his career in Washington as a lawyer with the National Labor Relations Board and later helped represent Hollywood figures subpoenaed by the House Un-American Activities Committee in the 1950s.
The couple met during annual summer camps at Lake Winnipesaukee. Mr. Rosenberg died in 1991 at 81.
They moved to West Newton in 1949, when he became a partner in a Boston law firm.
Mrs. Rosenberg sometimes worked as a backup typist for her husband’s firm, her family said. She helped him prepare court documents when he represented pediatrician and antiwar activist Benjamin Spock in the 1960s. Spock was convicted of conspiring to promote draft-dodging. His conviction was overturned on appeal.
Mrs. Rosenberg often enlisted her children to campaign outside polling places on Election Day. She helped found local antiwar groups in Newton and worked in a peace boutique that had opened to support the cause.
“She would send me around to the neighbors passing out brochures and collecting funds for one nonprofit or another,” son Joshua said. “She was always doing things. Anybody who came to her and needed some help, she always said yes.”
Her family attributed her long life to her genes and to her residency at Lasell Village, where she moved more than a decade ago.
At Lasell, Mrs. Rosenberg used a computer to write essays and e-mail her family, and she sang the Cole Porter tunes of her youth in the village choir.
“When she moved here to Lasell in her later years, she really opened up,” her daughter Lucy said. “She became more outspoken in her beliefs. She just said whatever she felt like, and everybody loved her for that.”
Her son Josh said he overheard Mrs. Rosenberg this spring making plans with a Lasell College student to campaign for President Obama’s reelection.
“I need you to go out there and work for Obama,” Mrs. Rosenberg told the young woman, according to her son. “Why don’t we go out together. We’ll go door to door. Maybe we’ll make an impression.”J.M. Lawrence can be reached at email@example.com.