She camped 26 days outside the Texas ranch of U.S. President George W. Bush to protest the Iraqi war last August.
This April, she and her supporters pitched their tents outside the ranch again, just to demand a reasonable answer as to why the U.S. troops are fighting and dying in Iraq.
But now, she is shifting her mission to a new direction.
Cindy Sheehan, the American anti-war icon, is on a cross-Canada tour. She urges the nation, which once sheltered so many U.S. Vietnam war dodgers, to give sanctuary to more American soldiers who have dodged service in Iraq or Afghanistan.
"I'm just here begging the people of Canada to force your government ... to allow our soldiers to have sanctuary up here," Sheehan, also known as "Peace Mom," told reporters on Thursday during her visit to the Parliament Hill in Ottawa.
The 48-year-old mother has become a leading voice in the American anti-war movement since her son, Casey, 24, was killed five days after he began serving in Iraq in 2004.
On Wednesday, she addressed an anti-war rally at the University of Toronto along with members of the Council of Canadians and the War Resisters Support Campaign. She is also scheduled to speak in Montreal and Vancouver.
Sheehan asked the Canadian government to create a provision allowing military deserters to flee to Canada so they do not need to apply for refugee status on an individual basis.
Canada became a haven for as many as 50,000 U.S. draft dodgers and deserters during the Vietnam war. That should happen again, Sheehan said.
"The peace movement in America has always looked up to Canada as refuge of peace and sanity when our leaders have taken us to insane wars."
Two American military deserters who arrived in Canada in 2004 - Jeremy Hinzman and Brandon Hughey - have been denied refugee status in Canada. They argued that the occupation of Iraq violates international human rights and is illegal.
Hinzman has appealed and the Federal Court is reviewing the decision. Many others are anxiously watching the case. There are 20 active refugee claims by American military deserters.
About 150 deserters are known to be living in Canada, according to the War Resisters Support Campaign, though the organization believes the number could be as high as 1,500. And there may be 8,000 others hiding out in the United States.
Describing the U.S. presence in Iraq as immoral and illegal, Sheehan recalled, in a sad, soft tone, her son told her before departure for Iraq that he disagreed with the war and the president's decision to send troops.
Sheehan then offered to drive him to Canada or even cripple him when her son learned in late 2003 that he would be sent to Iraq.
"I said: Casey, I'll do anything. I'll take you to Canada. Please let's go to Canada. Or if you don't want to go to Canada, I'll run you over with a car and break your legs, so please don't go."
She accused the U.S. army of luring impressionable young people into the ranks with false promises though it is now an all-volunteer force.
"Our children are lied to when they are recruited, they are recruited irresponsibly with deception," Sheehan said, adding that her son and other soldiers were told they would not be forced to participate in war if they signed up.
Even volunteers should be able to "un-volunteer" rather than be forced into a war they see as illegal, she said. "My son joined the army to help build the country, not to kill the innocent Iraqis."
Sheehan also urged Canada to get out of Afghanistan, which she said is just "a branch office of a immoral and illegal American-led war in Iraq."
When asked about an earlier decision by the Canadian government to ban media coverage on the return of dead soldiers' bodies from Afghanistan, she said: "I believe it's a propaganda tactic to keep the cost of the war away from the public."
The Tory government led by Prime Minister Stephen Harper sparked a furor last week when it announced the ban.
Defence Minister Gordon O'Connor claimed the sad homecomings at a military base would be closed to the media out of respect for the families of the slain.
But many observers believe the minority government is trying to mask the brutality of the Afghan mission which would undermine the Tory's broadening support base for winning a majority government in the next election.
Despite accusations that she is capitalizing on her son's death, Sheehan said she remained committed to her cause, though the stress of losing her son also affected her 28-year marriage.
The couple separated last June and her husband, Patrick, filed for divorce on Aug. 12, citing irreconcilable differences, while she was camping outside Bush's ranch.
"When you bury a child, there's not much else that can hurt you," Sheehan said. "That's the worst thing a mother can do ...if people think that calling me names or lying about me or twisting my words is going to stop me, they're wrong, because we're just trying to save lives."