For four years, ground battles involving tens of thousands of soldiers and horses were fought in Virginia, Maryland, Pennsylvania, Tennessee, and Georgia. Naval battles were fought off the Atlantic coast and on the Mississippi River. In that area, Union forces won an almost uninterrupted series of victories. In Virginia, by contrast, they met defeat after defeat in their attempts to capture Richmond, the Confederate capital.

The single bloodiest day of the war was on September 17, 1862, when the two armies met at Antietam Creek near Sharpsburg, Maryland. Confederate troops led by General Robert E. Lee failed to force back the Union troops led by General George McClellan, and Lee escaped with his army intact. McClellan was fired. Although the battle was inconclusive in military terms, its consequences were enormous. Britain and France had been planning to recognize the Confederacy. They delayed their decisions, and the South never received the aid it desperately needed.

Several months later, President Lincoln issued a preliminary Emancipation Proclamation. It freed all slaves living in Confederate states and authorized the recruitment of African Americans into the Union army. Now the North was no longer fighting just to preserve the Union. It was fighting to end slavery.

Union forces gained momentum in 1863 with victories at Vicksburg in Mississippi and Gettysburg in Pennsylvania, and then with the scorched-earth policy of General William T. Sherman as he marched across Georgia and into South Carolina in 1864. By April 1865, huge Union armies under the command of General Ulysses S. Grant had surrounded Robert E. Lee in Virginia. Lee surrendered, and the American Civil War was over.

The terms of surrender were generous. "The rebels are our countrymen again," Grant reminded his troops. In Washington, President Lincoln was ready to begin the process of reconciliation. He never got the chance. Less than a week after the South surrendered, he was assassinated by a Southerner embittered by the defeat. The task would fall to Lincoln's vice president, Andrew Johnson, a Southerner who favored quick and easy "Reconstruction."

Johnson issued pardons that restored the political rights of many Southerners. By the end of 1865, almost all former Confederate states had held conventions to repeal the acts of secession and to abolish slavery, but all except Tennessee refused to ratify a constitutional amendment giving full citizenship to African Americans. As a result, Republicans in Congress decided to implement their own version of Reconstruction. They enacted punitive measures against former rebels and prevented former Confederate leaders from holding office. They divided the South into five military districts administered by Union generals. They denied voting rights to anyone who refused to take a loyalty oath to the Union. And they strongly supported the rights of African Americans. President Johnson tried to block many of these policies and was impeached. The vote fell short, and he remained in office, but Congress would continue to wield enormous power for the next 30 years.

The divisions and hatreds that had led to the Civil War did not disappear after the fighting stopped. As Southern whites regained political power, Southern blacks suffered. They had gained their freedom but were prevented from enjoying it by local laws denying them access to many public facilities. They had gained the right to vote but were intimidated at the polls. The South had become segregated and would remain so for 100 years. The postwar Reconstruction process had begun with high ideals but collapsed into a sinkhole of corruption and racism. Its failure deferred the struggle for equality for African Americans until the 20th century, when it would become a national, not just a Southern, issue.