I think that had Lee realized that Lincoln would never come to his senses, he would have entered D.C. when he had the chance, and won the war fairly quickly.
Lee, in my opinion was fighting a DEFENSIVE WAR, protecting his homeland, and the rest of the South. His tactics and abilities were proven over, and over. But one can only sustain for so long in that mode, and Lincoln was not the man that Lee hoped he was.
Lee commanded with honor, while his adversary commanded FOR PROFIT AND PILLAGE.