Andrew Johnson in the context of "1864 National Union National Convention"

The Reconstruction era was a period in US history that followed the American Civil War (1861–1865) and was dominated by the legal, social, and political challenges of the abolition of slavery and reintegration of the former Confederate States into the United States. Three amendments were added to the United States Constitution to grant citizenship and equal civil rights to the newly freed slaves. To circumvent these, former Confederate states imposed poll taxes and literacy tests and engaged in terrorism to intimidate and control African Americans and discourage or prevent them from voting.

Throughout the war, the Union was confronted with the issue of how to administer captured areas and handle slaves escaping to Union lines. The United States Army played a vital role in establishing a free labor economy in the South, protecting freedmen's rights, and creating educational and religious institutions. Despite its reluctance to interfere with slavery, Congress passed the Confiscation Acts to seize Confederates' slaves, providing a precedent for President Abraham Lincoln to issue the Emancipation Proclamation. Congress established a Freedmen's Bureau to provide much-needed food and shelter to the newly freed slaves. As it became clear the Union would win, Congress debated the process for readmission of seceded states. Radical and moderate Republicans disagreed over the nature of secession, conditions for readmission, and desirability of social reforms. Lincoln favored the "ten percent plan" and vetoed the Wade–Davis Bill, which proposed strict conditions for readmission. Lincoln was assassinated in 1865, just as fighting was drawing to a close. He was replaced by Andrew Johnson, who vetoed Radical Republican bills, pardoned Confederate leaders, and allowed Southern states to enact draconian Black Codes that restricted the rights of freedmen. His actions outraged many Northerners and stoked fears the Southern elite would regain power. Radical Republicans swept to power in the 1866 midterm elections, gaining majorities in both houses of Congress.

On April 14, 1865, Abraham Lincoln, the 16th president of the United States, was shot at Ford's Theatre in Washington, D.C., one month into his second term and towards the conclusion of the American Civil War. Lincoln was watching the play Our American Cousin with his wife Mary Todd, Major Henry Rathbone, and Rathbone's fiancé Clara Harris when John Wilkes Booth, an actor and Confederate sympathizer, shot him in the head. Lincoln was taken to the Petersen House across the street, where he died the following morning.

With Union victory imminent, Booth and his conspirators, including Lewis Powell, David Herold, and George Atzerodt, originally plotted to kidnap Lincoln to aid the Confederacy. After that plan failed to materialize, they decided to assassinate him, Secretary of State William H. Seward, and Vice President Andrew Johnson. Booth hoped that eliminating the three most important officials of the federal government would revive the Confederate cause. Powell and Herold were assigned to kill Seward, while Atzerodt was assigned to kill Johnson. Booth succeeded in killing Lincoln, but Powell only managed to wound Seward, while Atzerodt became drunk and never targeted Johnson.

Abraham Lincoln's tenure as the 16th president of the United States began on March 4, 1861, and ended upon his death on April 15, 1865, 42 days into his second term. Lincoln, the first Republican president, successfully presided over the Union victory in the American Civil War, which dominated his presidency and resulted in the end of slavery in the United States. He was succeeded by Vice President Andrew Johnson.

Lincoln took office following the 1860 presidential election, in which he won a plurality of the popular vote in a four-candidate field. Almost all of Lincoln's votes came from the Northern United States, as the Republicans held little appeal to voters in the Southern United States. A former Whig, Lincoln ran on a political platform opposed to the expansion of slavery in the territories. His election served as the immediate impetus for the outbreak of the Civil War. After being sworn in as president, Lincoln refused to accept any resolution that would result in Southern secession from the Union. The Civil War began weeks into Lincoln's presidency with the Confederate attack on Fort Sumter, a federal installation located within the boundaries of the Confederacy.

The Reconstruction Amendments, or the Civil War Amendments, are the Thirteenth, Fourteenth, and Fifteenth amendments to the United States Constitution, adopted between 1865 and 1870. The amendments were a part of the implementation of the Reconstruction of the American South which occurred after the Civil War.

The Thirteenth Amendment (proposed in 1864 and ratified in 1865) abolished slavery and involuntary servitude, except for those duly convicted of a crime. The Fourteenth Amendment (proposed in 1866 and ratified in 1868) addresses citizenship rights and equal protection of the laws for all persons. The Fifteenth Amendment (proposed in 1869 and ratified in 1870) prohibits discrimination in voting rights of citizens on the basis of "race, color, or previous condition of servitude."

Moderate Republicans were a faction of American politicians within the Republican Party from the party's founding before the American Civil War in 1854 until the end of Reconstruction in the Compromise of 1877. They were known for their loyal support of President Abraham Lincoln's war policies and opposed the more militant stances advocated by the Radical Republicans. According to historian Eric Foner, congressional leaders of the faction were James G. Blaine, John A. Bingham, William P. Fessenden, Lyman Trumbull, and John Sherman. Their constituencies were primarily residents of states outside New England, where Radical Republicanism garnered insufficient support. They included "Conservative Republicans" and the moderate Liberal Republicans, later also known as "Half-Breeds".

During the 1864 United States presidential election, amidst the backdrop of the ongoing Civil War, moderate Republicans supported merging the Republican Party with the War Democrats (Democrats who supported the continuation of the Union war effort) to form the National Union Party alliance. At the Republican National Convention (which operated under the name of the "National Union National Convention" that year), they spearheaded the effort to replace Lincoln's vice president Hannibal Hamlin with Tennessee Democrat Andrew Johnson, acting out of the belief that placing a War Democrat on the presidential ticket would solidify support to ensure Lincoln's re-election.

The conclusion of the American Civil War commenced with the articles of surrender agreement of the Army of Northern Virginia on April 9, at Appomattox Court House, by General Robert E. Lee and concluded with the surrender of CSS Shenandoah on November 6, 1865, bringing the hostilities of the American Civil War to a close. Legally, the war did not end until a proclamation by President Andrew Johnson on August 20, 1866, when he declared "that the said insurrection is at an end and that peace, order, tranquillity, and civil authority now exist in and throughout the whole of the United States of America." The Confederate government being in the final stages of collapse, the war ended by debellatio, with no definitive capitulation from the rapidly disintegrating Confederacy; rather, Lee's surrender marked the effective end of Confederate military operations. The Confederate cabinet held its final meeting on May 5, at which point it declared the Confederacy dissolved, ending its substantive existence; despite this, some remnant Confederate units did not surrender for another month.

Lee's defeat on April 9 began the effective end of the war, after which there was no substantial resistance, but the news of his surrender took time to spread and some fighting continued, though only small skirmishes. President Abraham Lincoln lived to see Lee's surrender after four bloody years of war, but he was assassinated just five days later. The Battle of Columbus, Georgia, was fought on April 16, the day after Lincoln died. For the most part though, news of Lee's defeat led to a wave of Confederate surrenders. Gen. Joseph E. Johnston surrendered his large Army of Tennessee and the Southeastern Department on April 26. The Confederate cabinet was dissolved on May 5, and Confederate president Jefferson Davis was captured by Union soldiers on May 10, one day after Lincoln's successor, Andrew Johnson, declared that the belligerent rights of the Confederacy were at an end, with the rebellion effectively over.

The 40th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C. from March 4, 1867, to March 4, 1869, during the third and fourth years of Andrew Johnson's presidency. The apportionment of seats in the House of Representatives was based on the 1860 United States census. Both chambers had a Republican majority. In the Senate, the Republicans had the largest majority a party has ever held.

This Congress was held during the Reconstruction era after the Civil War and U.S. President Abraham Lincoln's assassination. Arkansas, Florida, Alabama, North Carolina, Louisiana, and South Carolina were readmitted to representation in both the Senate and the House. Georgia was readmitted with representation in the House only. The Republican majority passed an amendment that became the 15th Amendment for voting rights.

John Wilkes Booth (May 10, 1838 – April 26, 1865) was an American stage actor who assassinated United States president Abraham Lincoln at Ford's Theatre in Washington, D.C., on April 14, 1865. A member of the prominent 19th-century Booth theatrical family from Maryland, he was a noted actor who was also a Confederate sympathizer; denouncing Lincoln, he lamented the then-recent abolition of slavery in the United States.

Originally, Booth and his small group of conspirators had plotted to kidnap Lincoln to aid the Confederate cause. They later decided to murder him, as well as Vice President Andrew Johnson and Secretary of State William H. Seward. Although the Army of Northern Virginia, commanded by General Robert E. Lee, had surrendered to the Union Army four days earlier, Booth believed that the American Civil War remained unresolved because the Army of Tennessee of General Joseph E. Johnston continued fighting.

The chief justice of the United States is the chief judge of the Supreme Court of the United States and is the highest-ranking officer of the U.S. federal judiciary. Article II, Section 2, Clause 2 of the U.S. Constitution grants plenary power to the president of the United States to nominate, and, with the advice and consent of the United States Senate, appoint "Judges of the Supreme Court", who serve until they die, resign, retire, or are impeached and convicted. The existence of a chief justice is only explicit in Article I, Section 3, Clause 6 which states that the chief justice shall preside over the impeachment trial of the president; this has occurred three times, for Andrew Johnson, Bill Clinton, and for Donald Trump's first impeachment.

The chief justice has significant influence in the selection of cases for review, presides when oral arguments are held, and leads the discussion of cases among the justices. Additionally, when the court renders an opinion, the chief justice, if in the majority, chooses who writes the court's opinion; however, when deciding a case, the chief justice's vote counts no more than that of any other justice.