Which group was known as the de facto army of the Democratic Party during Reconstruction?

The Ku Klux Klan emerged during the Reconstruction era as a white supremacist organization that used violence and intimidation to undermine the rights of newly freed African Americans and to maintain white dominance in the South. They operated as a sort of "de facto army" for those who supported the Democratic Party, particularly in opposing the Reconstruction policies imposed by the Republican-led federal government. The Klan sought to disrupt Republican political events, intimidate voters, and violently retaliate against those who supported African American civil rights and the Reconstruction agenda. Their actions contributed to the terror and oppression faced by freedmen and their allies during this tumultuous period in American history, aligning closely with the interests of the Democratic Party at that time.

In contrast, the Freedmen's Bureau was established to aid formerly enslaved individuals in their transition to freedom, Carpetbaggers were northern transients who moved south to participate in the Reconstruction, and the Radical Republicans were a faction within the Republican Party that strongly supported civil rights for African Americans and aimed to impose strict measures on the Southern states. None of these groups operated in the same context of racial intimidation and violence as the Klan did.