Final answer:
Northern Republicans allowed the removal of federal troops from the South to ensure Rutherford B. Hayes's presidency, as part of the Compromise of 1877, leading to the end of Reconstruction.
Step-by-step explanation:
The northern Republicans agreed to the removal of troops from the South to ensure Rutherford B. Hayes would become president of the United States. This action was part of the informal agreement known as the Compromise of 1877. Following the contentious presidential election of 1876, this compromise was struck to resolve the disputed results and Hayes's contested electoral votes. Southern Democrats were given assurances that if Hayes became president, federal troops would be withdrawn from Louisiana and South Carolina, effectively ending Reconstruction and removing the enforcement mechanisms for protecting African American rights in the South. This allowed Southern Democrats to regain control of their local and state governments, which had a significant impact on the direction of southern politics and society in the following decades.