WikiLeaks released an enormous treasure-trove of classified US government documents in 2010. It included US military logs from the wars in Iraq and Afghanistan, over 250,000 diplomatic cables, and Collateral Murder, a video depicting the killing of 12 civilians by a US helicopter gunship in Iraq.
The source of the leaks, US Private Bradley Manning, acted on his conscience. He believed that people have a right to see the information he had been privy to as an army intelligence analyst. He was prepared to risk his life and liberty to reveal that information.