From PBS - In the spring of 1964, the civil rights community is gearing up for "Mississippi Freedom Summer," during which hundreds, if not thousands, of mostly white student activists from the North will link up with mostly black freedom workers to accomplish what the Mississippi power structure fears the most: registering black people to vote. For the segregationists, Freedom Summer is nothing less than a declaration of war. The state responds by swearing in hundreds of new deputies, stockpiling tear gas and riot gear, and preparing the jails for an influx of summer "guests." But the most powerful men in the state have another weapon to fight integration. They have quietly created a secret, state-funded spy agency, the Mississippi State Sovereignty Commission, answering directly to the Governor. During the height of the civil rights movement, sovereignty commission operatives employed a cadre of black operatives who infiltrated the movement, rooting out its future plans, identifying its leaders, and tripping up its foot soldiers. By gaining the trust of civil rights crusaders, they gathered crucial intelligence on behalf of the segregationist state.