What did Lee help do at the civil war?

Greatest significance that General Robert E. Lee had during the Civil Wars' battles was his command of the Army of Northern Virginia. His leadership, military brilliance, and choice of competent commanders led the Confederate forces in the East with victories and making the best of the situation when in defeat. He was able to keep the Federal forces at bay for years until Grant took command, even then, Grant realized that he could only bet Lee in a war of attrition and paid a heavy price for slowly wearing down the Confederates. He also recognized the importance of foreign intervention and how a victory on Northern soil would bring it about. However in both of his "invasions" of the North he had not been able to decimate the Army of the Potomac. He was able to do what no other man could do with what he had and is perhaps the most beloved general in American History, his own men cheering him after the infamous "Pickett's Charge".