American Civil War, widely known in the United States as simply the Civil War as well as other sectional names, was a civil war fought from 1861 to 1865 to determine the survival of the Union or independence for the Confederacy.

Among the 34 states as of January 1861, seven Southern slave states individually declared their secession from the United States and formed the Confederate States of America, known as the “Confederacy” or the “South”.

They grew to include eleven states, and although they claimed thirteen states and additional western territories, the Confederacy was never diplomatically recognized by a foreign country.

The states that remained loyal and did not declare secession were known as the “Union” or the “North”.

The war had its origin in the fractious issue of slavery, especially the extension of slavery into the western territories.

The American Civil War was one of the earliest true industrial wars.

Railroads, the telegraph, steamships, and mass-produced weapons were employed extensively.

The mobilization of civilian factories, mines, shipyards, banks, transportation and food supplies all foreshadowed World War I.

It remains the deadliest war in American history, resulting in the deaths of an estimated 750,000 soldiers and an undetermined number of civilian casualties.

One estimate of the death toll is that ten percent of all Northern males 20–45 years old, and 30 percent of all Southern white males aged 18–40 died.

George B. McClellan–who replaced the aging General Winfield Scott as supreme commander of the Union Army after the first months of the war–was beloved by his troops, but his reluctance to advance frustrated Lincoln.

In the spring of 1862, McClellan finally led his Army of the Potomac up the peninsula between the York and James Rivers, capturing Yorktown on May 4.

The combined forces of Robert E. Lee and Jackson successfully drove back McClellan’s army in the Seven Days’ Battles (June 25-July 1), and a cautious McClellan called for yet more reinforcements in order to move against Richmond.

Lincoln refused, and instead withdrew the Army of the Potomac to Washington.

By mid-1862, McClellan had been replaced as Union general-in-chief by Henry W. Halleck, though he remained in command of the Army of the Potomac.

Lincoln had used the occasion of the Union victory at Antietam to issue a preliminary Emancipation Proclamation, which freed all slaves in the rebellious states after January 1, 1863.

He justified his decision as a wartime measure, and did not go so far as to free the slaves in the Border States loyal to the Union.

Still, the Emancipation Proclamation deprived the Confederacy of the bulk of its labor forces and put international public opinion strongly on the Union side.

Some 186,000 black soldiers would join the Union Army by the time the war ended in 1865, and 38,000 lost their lives.

An immediate counterattack reversed the victory, however, and on the night of April 2-3 Lee’s forces evacuated Richmond.

For most of the next week, Grant and Meade pursued the Confederates along the Appomattox River, finally exhausting their possibilities for escape. Grant accepted Lee’s surrender at Appomattox Court House on April 9.

On the eve of victory, the Union lost its great leader: The actor and Confederate sympathizer John Wilkes Booth assassinated President Lincoln at Ford’s Theatre in Washington on April 14.