Fonda's transformation from actress to activist began several years earlier. She was active in the Black Panthers and marched for the rights of native Americans, soldiers and working mothers. But she was advised by other activists to focus her political energies, deciding to go all-in as an impassioned voice for the antiwar movement.
She and actor Donald Sutherland started an "anti-USO" troupe to counter Bob Hope's famous shows for the troops.
They called it FTA, which they said stood for Free the Army, but it was also a not-so-subtle nod to the expression "**** the Army."
By July 1972, when Fonda accepted an invitation to visit North Vietnam, America had been at war overseas and with itself for years. She went to tour the country's dyke system, rumoured to have been intentionally bombed by American forces - something the US government to this day denies. During her two-week stay, Fonda concluded that America was unjustly bombing farmland and areas far flung from military targets. North Vietnamese press reported - and Fonda confirmed - that she made several radio announcements over the Voice of Vietnam radio to implore US pilots to stop the bombings.
She said the radio addresses were the only way to get access to American soldiers.
In Hanoi, Fonda also met with seven American POWs and later said they asked her to tell their friends and family to support presidential candidate George McGovern; they feared they'd never be freed during a Richard Nixon administration. Rumours spread and still persist that she betrayed them by accepting secret notes and then turning them over to the North Vietnamese. The POWs who were there have denied that this ever occurred.
But the action that still enrages veterans most was that photo of her with the Viet Cong on an anti-aircraft gun that would have been used to shoot down American planes. This, probably more than anything, earned her the nickname "Hanoi Jane".
After Fonda returned from her trip, the State Department spoke out against her.
"It is always distressing to find American citizens who benefit from the protection and assistance of this government lending their voice in any way to governments such as the Democratic Republic of Vietnam - distressing indeed," said State Department spokesman Charles W. Bray, according to a July 1972 Reuters story.
Some lawmakers called her actions treason. Congress held hearings. The Veterans of Foreign Wars passed a resolution calling for her to be prosecuted as a traitor.
Fonda wasn't deterred. She continued openly to question the accounts of the US government and American POWs, who told devastating stories of the torture they endured at the hands of the North Vietnamese.
"These men were bombing and strafing and napalming the country," she said, according to an Associated Press report in April 1973. "If a prisoner tried to escape, it is quite understandable that he would probably be beaten and tortured."
Over the years, as Fonda reinvented herself as a fitness maven and again a movie star, she apologised many times for the anti-aircraft gun photo. But she maintains she was not a traitor by speaking out against the war or trying to turn soldiers against it.
Still, for some veterans, no apology from Fonda will ever change their views of her as an adversary of America and the troops during wartime. In 2015, about 50 veterans stood outside the Weinberg Center for the Arts in Frederick, Maryland, to protest Fonda's appearance there. They held signs that read "Forgive? Maybe. Forget? Never." and booed people attending the event, according to the Frederick News-Post.
Fonda told the audience that their protests saddened her.
"It hurts me," she said, "and it will to my grave that I made a huge, huge mistake that made a lot of people think I was against the soldiers."
