Abraham Lincoln (February 12, 1809 – April 15, 1865) was the 16th president of the United States, serving from 1861 until his assassination in 1865. He led the United States through the American Civil War, defeating the Confederate States of America and playing a major role in the abolition of slavery.

Lincoln was born into poverty in Kentucky and raised on the frontier. He was self-educated and became a lawyer, Illinois state legislator, and U.S. representative. Angered by the Kansas–Nebraska Act of 1854, which opened the territories to slavery, he became a leader of the new Republican Party. He reached a national audience in the 1858 Senate campaign debates against Stephen A. Douglas. Lincoln won the 1860 presidential election, which the South viewed as a further threat to states' rights and slavery, and Southern states began seceding to form the Confederate States of America. A month after Lincoln assumed the presidency, Confederate forces attacked Fort Sumter, starting the Civil War.

Lincoln, a moderate Republican, had to navigate a contentious array of factions in managing conflicting political opinions during the war effort. Lincoln closely supervised the strategy and tactics in the war effort, including the selection of generals, and implemented a naval blockade of Southern ports.