There were basically 3 plans for Reconstruction, Lincoln’s plan, Johnson’s plan, and the Radical Republican plan.
Lincoln’s plan was known as the 10% Plan. It was simple. With a few exceptions, Lincoln offered pardons to any Confederate who swore allegiance to the Union and the Constitution. When the number of people who took an oath of allegiance equaled 10% of the number of voters who participated in the election of 1860, the state would be readmitted to the Union after organizing a new state government which abolished slavery. Lincoln was assassinated before this plan could be put into effect.
Johnson’s plan was also lenient towards the southern states. He would grant pardons to anyone taking a loyalty oath to the U.S. except for high ranking Confederate political and military leaders, and people owning property worth more than $20,000. States would be readmitted to the Union once they created a new state government that abolished slavery, repealed the state’s ordinance of secession, and repudiated Confederate debts. This was put into effect when Congress was in recess. Johnson’s Plan did not really address the fortunes of newly freed slaves and southern states began to pass “black codes”’ or laws which severely limited the civil rights of freedmen. When Congress reconvened, it refused to recognize Johnson’s plan by refusing to seat any person elected to Congress from any former Confederate state. It then began to pass its own laws concerning the southern states.
The Congressional Plan, or Radical Republican Plan, was meant to aid newly freed slaves (known as freedmen) and to punish the South. It first passed several laws helping newly freed slaves, such as The Civil Rights Act (whose provisions would later be found in the 14th Amendment). It also extended the life of the Freedmen’s Bureau. It then passed a series of laws known as The Reconstruction Acts. These laws were vetoed by Johnson, but the vetoes were easily overridden and these laws were put into effect. The Reconstruction Acts basically divided the South into 5 military districts with the military commander of the district given complete authority. No state would be allowed back into the Union until it ratified the 14th Amendment and guaranteed the right to vote for African American men. And later, for some states, the 15th Amendment had to be ratified, too. The 14th Amendment punished Confederate supporters and gave citizenship to former slaves. It also said that no state could deny to anyone, including African Americans, the equal protection of the law and due process of law. The 15th amendment stated that the right to vote could not be denied on the basis of race. Eventually all states were readmitted under this plan.
President Abraham Lincoln could see the writing on the wall by 1863, that the Union would most likely win the war, and the need for reconstruction of the national politically, economically and socially would be paramount. His idea was the 10% Plan, where if 10% of the number of people in a state that voted in the 1860 election swore allegiance to the Union (not 10% of the entire population, which would be harder), then the state could be readmitted. Johnson was from a border state, and he supported Lincoln's plan.
Radical Republicans in Congress, Thaddeus Stevens among them, believed this was way too lenient for what they considered traitors. He put forth the Conquered Province Theory, which suggested that the states shouldn't be readmitted at all, and that the people living inside those states were no longer citizens. He wanted to divide up the states into five military districts and run them by martial law as conquered provinces. But he was a radical, and the Congress eventually adopted Lincoln's plan.
Congress also put forth the 13th, 14th and 15th amendments, while no southern Democrats were yet in Congress and amendments were easier to pass. This abolished slavery, gave free blacks citizenship, and allowed black males 21 and older to vote.
Stevens' other idea was "40 Acres and a Mule", which would break up the old plantations and divide the land among the former slaves. This was a great idea, and would have worked, except it was never adopted.