Abraham Lincoln was born into poverty in a log cabin and was raised on the frontier primarily in Indiana. He was self-educated and became a lawyer, Whig Party leader, Illinois state legislator, and U.S. Congressman from Illinois. In 1849, he returned to his law practice but became vexed by the opening of additional lands to slavery. He reentered politics in 1854, becoming a leader in the Republican Party, and reached a national audience in the 1858 debates against Stephen Douglas. Lincoln ran for President in 1860, sweeping the North in victory. To secure its independence, the new Confederate States fired on Fort Sumter, a U.S. fort in the South, and Lincoln called up forces to suppress the rebellion and restore the Union.

Lincoln, a moderate Republican, had to navigate an array of factions with friends and opponents from both the Democratic and Republican parties. He managed the factions by exploiting their mutual enmity, carefully distributing political patronage, and by appealing to the American people. His Gettysburg Address appealed to nationalistic, republican, egalitarian, libertarian, and democratic sentiments. Lincoln scrutinized the strategy and tactics in the war effort, including the selection of generals and the naval blockade of the South's trade. He suspended habeas corpus in Maryland, and he averted British intervention by defusing the Trent Affair.