Final answer:
President Abraham Lincoln's strategy to secure the loyalty of the Border States during the Civil War and to reintegrate the Southern states into the Union was encapsulated in the Ten Percent Plan, which was a moderate approach aimed at rapid reunification and included an oath of allegiance to the U.S. and acceptance of the end of slavery.
Step-by-step explanation:
President Lincoln's Plan for the Border States
During the Civil War, President Abraham Lincoln developed a strategy to secure the loyalty of the border states and to restore the Southern states to the Union. He established the Ten Percent Plan, which was a lenient proposal aimed at encouraging Southern states to rejoin the Union swiftly. The plan required 10 percent of the voting population of a state, based on the 1860 election, to take an oath of allegiance to the United States and to accept the end of slavery. Successful implementation of this plan would allow those states to form new state governments and to be readmitted into the Union. The Ten Percent Plan effectively sidestepped the harsher measures that Radical Republicans wished to impose, hoping to facilitate a faster reunification and acceptance of emancipation.
However, this approach was met with resistance from many within Lincoln's own party, as the Radical Republicans believed it to be too forgiving. They sought a more stringent plan that would not only punish the Confederacy for secession but would also protect the rights of formerly enslaved individuals. Despite the pushback, Lincoln's focus remained on the quick restoration of the Union and avoiding further alienation of the border states through drastic changes or severe penalties for secession.
Ultimately, the Emancipation Proclamation and the Thirteenth Amendment set the stage for the abolition of slavery in the United States, but the complexities of Reconstruction and the future balance of power between presidential and congressional authority remained unresolved at the war's end, particularly after Lincoln's assassination.