I'm not familiar with the rape report that Claymore has sited and, although it might have indeed been the nominal call-to-arms to justify Klan activity, I feel the actual motivations for Klan organization run deeper.
The Freedmen's Bureau, established in 1865 to affirm the economic and political rights of blacks, was a humanitarian ideal realized, that became tainted through its accumulation of power. It did in fact accomplish much good, including gaining voting rights for blacks, and offering them educational opportunities that had never existed. Thousands of blacks, as well as poor whites, were given food and housing by this agency. The main source of its corruption came in the areas of economic redistribution of industry and land. It was relegated to the Bureau to annex and give over to former slaves some 800,000 acres of farm land, and to redistribute plantations and businesses in like manner, in an attempt to make reparations to blacks. Land was also promised to state residents determined to be loyal to the union, including recent arrivals. This process was highly resented by the white property-owners, who saw the Bureau as ceding land to northern speculators as well as the blacks.
Contrary to what Greg stated, the individuals known as "carpetbaggers" were nearly all white. Many were Freedmen Bureaucrats who not only assisted in what Southerners saw as theft of their property, but in the appointment or election of blacks and union-loyal whites to all government posts, through what amounted to pure bribery and manipulation of the vote. These carpetbagging governments were often dishonest and graft-ridden profit centers for their northern bosses.
I am not in any way attempting to defend the Klan. It has become a wretched organization dedicated to hate and fear. I am, however, attempting to examine the multitude of reasons which gave birth to it, and to declare that there were distinct reasons for its creation apart from the lynching and terrorization of blacks, and that it may indeed have begun as some sort of attempt at self-defense by a defeated people.