She then joined the Women’s Army Corps and was stationed at Fort Bragg, N.C. When an officer saw her walking with a Black soldier, she was reprimanded and sent to Panama as punishment.
There she was assigned to work in the Army’s pediatrics and obstetrics wards, where she saw women suffering from botched abortions as well as women being forced to give birth to babies they didn’t want.
After leaving the Army, she attended San Jose State College (now University) in California, where she became pregnant. She had been fitted for a diaphragm, but it hadn’t worked. Partly because of her parents’ examples, she was determined not to have the baby and ended up going to Mexico to have an abortion.
Once the Supreme Court ruled in its landmark Roe decision in 1973 that women had a constitutional right to abortion, Ms. Maginnis rechanneled her activism to other issues, including gay rights and animal welfare. She also staged regular protests against the Catholic Church, criticizing its anti-abortion policies and demanding accountability in cases of sexual abuse by priests.
In addition to a large extended family, Ms. Maginnis is survived by two sisters, Charlotte Palmer and Jane Bloom, and two brothers, Michael and Paul.
Always self-reliant, she bought a two-story Victorian house in East Oakland in 1979 and devoted much of her time to restoring it. It had been gutted by fire, and it had no foundation. But she created one by digging a two-foot trench around it herself with a serving spoon and hauling the dirt away in a small pot, which took her an entire year.
In her later years, she didn’t talk much about abortion unless asked. Ms. Bloom, her grandniece, said that she didn’t even know about Ms. Maginnis’s work until she was a student at Smith College and saw a documentary in which her great-aunt appeared.
“Even though the ‘Army of Three’ comes up in women’s studies courses,” Ms. Bloom said, “no one is reading whole books about them. And a lot of younger feminists don’t know about them.”