When Robert E. Lee took command of the Army of Northern Virginia, the Confederacy had reached desperate straits. He decided that only bold strategy could right the balance. At the outset his solution proved correct. By the end of August, 1862, Lee had virtually cleared Virginia of Federal troops. Success brought embarrassment, however, for it was impossible for the heavily outnumbered Southern army to pursue victory fully. Lee approached this dilemma as he approached the frontier of the Confederacy. On September 2, 1862, he chose from the courses open to him, all of which were unattractive in varying degrees, to try to stretch the definition of the defensive-offensive into larger meaning. This and not Pennsylvania, or foreign recognition, or revolution in Maryland, or boodle was the real objective of the Maryland campaign. Lee's expedition failed for three reasons. First, straggling had worn his army too thin by the crucial phase of the campaign. Second, Lee's opponent, George McClellan, advanced the Northern army from the Washington forts too cautiously to be trapped but too rapidly to give the Southern army the time it needed once it had divided to dear the Shenandoah Valley. Third, Lee made several tactical miscalculations which governed the form the failure assumed and hastened its happening. Twice he misinterpreted the Harpers Ferry problem, and once, but fatally, he misjudged McClellan's advance from Washington. In addition, his plans for the reduction of the enemy In the upper Valley were unnecessarily and detrimentally complicated. For the Federal commander, George McClellan, the Maryland campaign was a success without serious qualification. McClellan merged two armies, one thoroughly dispirited and both utterly disorganized, into a manageable field force In less than a week. He took the field with ambiguous authority and the active dislike of nearly all the politicians In Washington except Lincoln, and even the President did not trust the general. Laboring under exaggerated reports of the enemy's size, he pushed his army forward cautiously, in a defensive-offensive strategy which successively blocked Lee's avenues for maneuver. In retrospect, it can be seen that Lee and McClellan were cast In very different roles throughout the Maryland campaign. Neither the objectives nor the problems of the Southern army were the same as those of the Northern army. The irony was that both sides were compelled by circumstances to adopt the same strategy, the defensive-offensive. For Lee this strategy was a gamble. For McClellan it represented the path of sureness. For both It was the result of a realistic appraisal of the difficult situations which each faked.