It began with Chilean families banging pots and pans from their windows one evening in 1983.
Seven years later, on a bright autumn afternoon, a line of young Chileans sprinted into the national stadium in Santiago, unfurling behind them a billowing red, white, and blue national flag that covered the whole field. In one dramatic gesture, they symbolically reclaimed their flag from the military authorities who had once used the stadium as a concentration camp. The 1990 elections had removed coup leader Gen. Augusto Pinochet. Activists celebrated the peaceful end of one of Latin America's longest dictatorships.
"Taking power without using violence is often said to be impossible, until it happens. Then it's said to have been inevitable," says Peter Ackerman, co-author of "A Force More Powerful," a book about nonviolent conflicts over the past century.
Most famously, Mohandas Gandhi forced the British onto the defensive in India with his nonviolent campaigns. "People power" evicted Ferdinand Marcos from the Philippines presidential palace. The Solidarity movement in Poland chipped away at the pillars of Communist rule. Mass protests and international boycotts undermined apartheid in South Africa.
Elsewhere, such movements have failed; in Tiananmen Square, in Burma, in the West Bank and Gaza. In some countries, such as Iraq or North Korea, they have never got off the ground. The jury is still out on Venezuela's civic unrest.
When nonviolent uprisings fail, it is often because the governments leave so little political space in which opposition activists can organize without being arrested or worse, says John Crist at the US Institute of Peace in Washington. "Nonviolent resistance campaigns work best in places where there is some access to democratic principles such as freedom of communications" he says.
But determined and courageous activists can find ways to express themselves under even the toughest dictatorships, argues Mr. Ackerman. "There isn't political space if you believe there isn't, and there is if you believe there is," he says. "It's a self-fulfilling prophecy. You make space if you believe everyone else is willing to make space with you .... you need to do it in a way that people will know they won't be alone."
Among the critical factors, say experts:
• Realistic goals. "You need to have a goal everyone signs on to that is attainable," says Ackerman. Solidarity's initial ambition was an independent trade union - not an end to Communist rule.
• Depth. Lasting movements need midlevel activists to keep things going if leaders are killed or arrested. The Burmese opposition, focused almost exclusively on leader Aung San Suu Kyi, has failed to gain momentum.
A network of organizers can help connect a movement to a wider constituency, in the way that black church ministers spread the US civil rights movement among their congregations. Connecting with foreign donors, for cash and training, however, can be a double-edged sword, points out Zarko Korac, a former opposition activist in Yugoslavia who is now deputy prime minister of Serbia. "If they deal with you too much, you look like traitors," he says.
• Divide and conquer: Successful civilian resistance movements create splits within the ruling clique that isolate the ruler, and the movements need army and police troops to refuse to continue fighting the resisters.
"You never know how a dictatorship will come to an end," says Sonja Licht, who runs George Soros's Open Society Institute in Belgrade. "Each time it is a unique experience. But dictators fall if the power against them has been generated by the people. This has been ignored for years."
Generating that power can often take years, Ackerman acknowledges. "But when an idea catches on, it catches on like wildfire," he adds. "Extraordinary things can happen very, very quickly."