He is best known for commanding the Confederate Army of Northern Virginia in the American Civil War.
In early 1861, President Abraham Lincoln invited Lee to take command of the entire Union Army. Lee declined because his home state of Virginia was seceding from the Union, despite Lee's wishes. When Virginia seceded from the Union in April 1861, Lee chose to follow his home state.
Lee's greatest victories were the Seven Days Battles, the Second Battle of Bull Run, the Battle of Fredericksburg, the Battle of Chancellorsville, and the Battle of Cold Harbor but both of his campaigns to invade the North ended in failure. Barely escaping defeat at the Battle of Antietam in 1862, Lee was forced to return to the South.
In the final months of the Civil War, as manpower reserves drained away, Lee adopted a plan to arm slaves to fight on behalf of the Confederacy, but this came too late to change the outcome of the war. After Appomattox Lee encouraged reconciliation between the North and the South.
After the war, as a college President, Lee supported President Andrew Johnson's program of Reconstruction and inter-sectional friendship. Lee became the great Southern hero of the war, and his popularity grew in the North as well after his death in 1870. He remains an iconic figure of American military leadership.