What prompted the shift to Congressional reconstruction?

The shift to Congressional Reconstruction was primarily prompted by the election of former Confederates to positions of power in the Southern states following the Civil War. This development alarmed many members of Congress, particularly the Radical Republicans, who felt that the reintegration of these former Confederates posed a threat to the gains made for African American rights and the overall direction of Reconstruction.

Members of Congress viewed the actions of the Southern states as a sign that they were not genuinely committed to the reconstruction effort or to upholding the rights of freedmen. The concern was that the Southern states might revert to pre-war attitudes and policies, undermining any advances in civil rights and social justice. Congressional Reconstruction aimed to impose stricter conditions on the Southern states and ensure federal oversight to establish equitable governance and protect the rights of newly freed African Americans.

The other options reflect various aspects of the post-war context but do not directly address the urgent political circumstances that led Congress to take control of Reconstruction efforts. Economic recovery and success in plantations do not capture the immediate political shifts that mandated Congressional action, and the need for military leaders' support was secondary to the pressing issue of political power in the South being regained by former Confederates.