What was the largest protest in history?

The Earth is currently home to an estimated 7 billion people, distributed among roughly 240 countries, 6,912 languages and more branches of religion and personal belief than can be counted easily. Our numbers continue to grow to this day.

Yet there are still events and causes that can unite mere millions of us. Wars have long brought together millions in pitched battles. In 480 B.C., the Persian Army marched into the Battle of Thermopylae with between 200,000 and 500,000 men. More than 2,000 years later, in 1943, the Soviet Union's Red Army suffered more than a million casualties at the Battle of Stalingrad. Still, humans often come together for reasons that don't involve massive invasions by foreign forces. During January 2007, an estimated 60 million Hindu pilgrims gathered at the convergence of the Ganges and Yamuna rivers in northern India for the Ardh-Kumbh Mela, or festival [source: BBC].

When it comes to protests, the book of Guinness World Records currently lists the Feb. 15, 2003, Iraq War protest in Rome as the largest antiwar rally in history. The event drew an estimated crowd of 3 million. On that same day, protesters gathered in nearly 600 cities in a coordinated global effort to express moral outrage against the U.S. invasion of Iraq. This included a reported 1.3 million protesters in Barcelona, Spain, and between 750,000 and 2 million protesters in London [sources: Guinness Book of World Records, BBC]. All told, between 6 and 10 million people participated in the global protest [source: BBC].

Of course, not all protests are rallies. During the early 20th century, Mahatma Gandhi led millions of Indians in protest against British rule through noncompliance. Indian public officials resigned, parents withdrew their children from British schools and participants boycotted British goods. Exact figures for such a movement are difficult to calculate.

Next we'll look at the controversial 2012 anti-piracy bills that triggered the largest online protest in history.

On January 18, 2012, the Internet went dark. OK, not exactly, but it felt that way to regular visitors to sites like Wikipedia, Craigslist, Wordpress and Wired. These high-profile sites – and more than 100,000 others -- shut themselves down for the day to protest two bills in Congress that critics claimed would censor the Web and stifle innovation. The shuttering of so many high-traffic sites, and calls to action by major players like Google, snowballed into the biggest online protest in history.

First, some background: The two pieces of proposed legislation were called the Stop Online Piracy Act (SOPA) and the Protect IP Act (PIPA). Both bills were designed to fight the global epidemic of intellectual property theft. Supporters of the bills, like the Motion Picture Association of America and the Recording Industry Association of America, pointed to the billions of dollars lost each year to file-sharing sites that offer illegal downloads of movies and songs. SOPA and PIPA would give the U.S. Justice Department and copyright holders new tools to shut down these sites or at least bar advertisers and payment sites like PayPal from doing business with them [source: Plumer].

Under existing law, known as the Digital Millennium Copyright Act, a Web site hosting copyright material receives a notice to take down the offending file or be subject to legal action. The big problem with SOPA and PIPA, opponents claim, is that the bills would give copyright owners unfettered power to shut down Web sites without warning or a court order. The result, critics feared, would be unchecked censorship of small, out-gunned sites by big media players. Opponents of the bill also wondered what would happen if media companies began "de-listing" offending Web sites from the Internet. Such tampering with the underlying architecture of the Internet sparked outcry that SOPA and PIPA would "break the Internet" [source: Yu].

The Senate was scheduled to vote on SOPA and PIPA on January 24, 2012. For months leading up to the vote, opposition Web sites had organized small grassroots protests and town hall meetings to draw attention to the bills and encourage concerned citizens to contact their representatives. Still, by mid-January, only a handful of senators had spoken out in opposition of the legislation.

That would all change on January 18. Thanks to the very public outage of Wikipedia and vocal opposition by Google, nearly 10 million people signed online petitions opposing SOPA and PIPA. Over 4 million people sent e-mails to their congressmen and women. And almost a billion people were blocked from visiting "striking" Web sites. Dozens of senators quickly withdrew their support for the bill and the January 24th vote was suspended indefinitely.