The Civil War in the United States began in 1861, after decades of simmering tensions between northern and southern states over slavery, states’ rights, and westward expansion. The election of Abraham Lincoln in 1860 caused seven southern states to secede and form the Confederate States of America; four more states soon joined them.
The War Between the States, as the Civil War was also known, ended in Confederate surrender in 1865. The conflict was the costliest and deadliest war ever fought on American soil, with some 620,000 of 2.4 million soldiers killed, millions more injured and much of the South left in ruin.

In the mid-19th century, while the United States was experiencing an era of tremendous growth, a fundamental economic difference existed between the country’s northern and southern regions.

In the North, manufacturing, and industry was well established, and agriculture was mostly limited to small-scale farms, while the South’s economy was based on a system of large-scale farming that depended on the labor of Black enslaved people to grow certain crops, especially cotton and tobacco.

In 1854, the U.S. Congress passed the Kansas-Nebraska Act, which essentially opened all new territories to slavery by asserting the rule of popular sovereignty over congressional edict. Pro- and anti-slavery forces struggled violently in “Bleeding Kansas,” while opposition to the act in the North led to the formation of the Republican Party, a new political entity based on the principle of opposing slavery’s extension into the western territories.

In the early morning hours of April 12, 1861, rebels opened fire on Fort Sumter, at the entrance to the harbor of Charleston, South Carolina. Curiously, this first encounter of what would be the bloodiest war in the history of the United States claimed no victims.
After a 34-hour bombardment, Maj. Robert Anderson surrendered his command of about 85 soldiers to some 5,500 besieging Confederate troops under P.G.T. Beauregard. Within weeks, four more Southern states (Virginia, Arkansas, Tennessee, and North Carolina) left the Union to join the Confederacy.

In April 1862 Congress abolished slavery in the District of Columbia and paid owners in the district about $300 on average for each slave. Three months later Congress passed the Second Confiscation Act, which mandated that any Confederate civilian or military official who did not surrender within 60 days would have his slaves freed. Two days after that, Congress banned slavery from the territories.