Final answer:
Under Lincoln's plan for Reconstruction, 10 percent of a state's population had to swear an oath of loyalty to the Union for the state to be readmitted.
Step-by-step explanation:
Under Lincoln's plan for Reconstruction, 10 percent of a state's population had to swear an oath of loyalty to the Union for the state to be readmitted. This plan was known as the Ten Percent Plan. It aimed to quickly restore the Southern states to the Union after the Civil War. This percentage was relatively low compared to later measures imposed during Reconstruction.
Learn more about Lincoln's plan for Reconstruction