Continuing my Wikibox TL (which needs a name...)
The assassination of President Chamberlain and his predecessor President Hamlin shocked the nation. Never before had an assassin slain a President. Attempts had been made, to be sure, but never had there been a successful murder of the nation's executive.
The assassins David Edgar Herold and John Wilkes Booth were quickly apprehended and sentenced to death, but Southern sympathizers smuggled in pistols, which the two used to kill themselves before their executions.
The death of Chamberlain left his Vice president, Lovell Harrison Rousseau as the new president. The Kentuckian Rousseau had been somewhat wary of Chamberlain and Hamlin's Reconstruction plans, but the assassination turned Northern sentiment to a fever pitch in favor of Reconstruction. And Rousseau himself, a former member of the House of Representatives (from 1866-1869) and a Union brevet general, was eager to punish those who seemed determined to restart the Civil War.
In what historians later called The Kentucky Plan, Rousseau worked with Republicans in Congress to strengthen the lenient Chamberlain Reconstruction policies, requiring a higher percentage to swear loyalty to the Union and barring Confederate officers from holding office for twenty years. Furthermore, federal spies and scouts were sent throughout the South, investigating and arresting guerrilla commanders who refused to give up the Confederate fight. Rousseau himself commented that the South "had tempted the judgment of God and the United States Army upon it".
Additionally, Rousseau, while no friend to abolitionism and black rights himself, supported the installation of several black governors and senators throughout the South. He confiscated the large plantations of several former slaveholders who were found to have supported the Chamberlain asssassins, and gave them to a collection of poor blacks and poor whites, intending to build a powerful mixed middle class to rival the old planter families. Not wanting to overthrow the established order entirely, however, Rousseau left many plantations in place.
Under the guise of aiding poor whites whose education suffered during the Civil War, schools for a mix of poor whites and former slaves were also established across the South, with Rousseau sending the celebrated Frederick Douglass as sort of unofficial regional superintendent of education, along with a regiment of federal troops to protect Douglass from any pro-Confederate assassins. Douglass made a point of educating both blacks and whites in his schools.
The last of Rousseau's Reconstruction plans were the Enforcement Acts of 1871. The acts made it a crime to deprive former slaves of their civil rights, and ensured the legal protection of blacks serving on juries and in elected office. An Radical Republican amendment to the acts even ensured the deployment of federal troops to county seats if the Department of War felt black civil rights were being violated. However, the enforcement of the Enforcement Acts were unevenly applied, and high-profile violations of the Acts often garnered more attention than less prominent cases.
Apart from Reconstruction, the Rousseau administration also continued the Chamberlain administration's foreign policy, and in 1874, with the reluctant support of the dying Senator Charles Sumner, passed a treaty of annexation of the Dominican Republic, which became known as the Territory of Santo Domingo. Unfortunately for the administration, the annexation proved to be a bridge too far, and the pushback from the voting public forced the Republicans out of power in the Senate, precluding any attempts to make the island a state.
An economic depression in 1875 further hampered Rousseau's woes, and his continuation of Chamberlain's Indian policy did not achieve any lasting positive results, though nor did it end in massacres and violence like many Indian policies did.
While Rousseau easily defeated the Democratic nominee in 1872, with certain defeat looming, he declined to run for re-election in 1876, turning over the White House to Democratic Senator George B. McClellan[1] of New Jersey in March of 1877. He retired to his home in Kentucky and spent the rest of his life there, acting as an elder statesman in Kentucky politics. While he was hated during his life, modern historians generally consider Rousseau to be an underrated president, excellent on civil rights, but facing great opposition in many other polices.
[1] McClellan was not a general in the ATL Civil War, which is all I'll say for now.