The Civil War lasted from 1861 to 1865. It started when eleven Southern states declared secession from the Union and formed the Confederate States of America. The Confederate leader was Jefferson Davis. The Confederacy fought against the US federal government (the Northern states), which was supported by all the free states and the five border states in the north.
The Republican Party led by Abraham Lincoln led an election campaign in the presidential election in 1860 which had as one of its main objectives to prevent slavery from extending to new states beyond where it already existed. The Republican electoral victory led seven Southern states to declare their separation from the Union even before Lincoln took office on March 4, 1861.
The hostilities began on April 12, 1861, when Confederate forces attacked a U.S. military installation at Fort Sumter in South Carolina. Lincoln responded by asking for a volunteer army from each state, leading to another four slave states in the south erupting. Both sides assembled armies while the Union took control of border states early in the war and established a naval blockade. In September 1862, the Emancipation Proclamation made abolishing slavery in the South a war cause, making it difficult for Britain to intervene on the Confederacy's side.
Confederate commander Robert E. Lee won the battle in the east, but in 1863 his advance to the north was fought back in Gettysburg, and in the west the Union gained control of Mississippi in the Battle of Vicksburg. Thus, the Confederacy was divided into two. Long-term benefits to the Union in terms of manpower and materiel were exploited in 1864 when Ulysses S. Grant fought exhaustion battles against Lee, while Northern States General William Tecumseh Sherman captured Atlanta in Georgia and marched to the sea. Confederate resistance collapsed after Lee surrendered to Grant at Appomattox Court House on April 9, 1865.
The Civil War was the deadliest war in American history, leading to 620,000 dead soldiers and an unknown number of civilian casualties. It ended slavery in the United States, reintroduced the Union and strengthened the position of the federal government. The social, political, economic and racial issues of the war greatly shaped the Reconstruction that lasted until 1877 and led to changes that helped the country become a superpower in the 20th century.
