Most of the great generals accomplished great things with great armies.
General Lee did so with a rag-tag bunch of ill-equiped militia and civilians. He faced one of the best equiped, best trained and best supplied armies in the world. He met their main forces 6 times. He lost twice, tied once, and beat them soundly 3 times. Considering the differences in the logistics, training and equipment between the union and the conferates, the war should not have lasted 6 months.
He is also the best example of the US Military's code of "an officer and a gentleman". When the war broke out, he was made a general. However, he refused to wear ensignia of a rank higher than colonel.
Had the Texas militia had the balls, the Civil War could have ended much sooner. Col. Lee was in command of forces in Texas (General Twiggs was away on business concerning the upcoming secession) when Texas militia approached Lee's command demanding they surrender. Lee refused to surrender, and the texans left. Had they fired the first shots, instead of those in South Carolina, Lee would have commanded forces in the Union Army and the south would have lost much sooner. (Lee later wrote that he would not have resigned his commission during wartime)