Brig. Gen. William N. Pendleton. The Second Corps was organized with artillery attached to each division, in contrast to the First Corps, which reserved its artillery at the corps level. One of the more unusual aspects of the Maryland campaign was the severely understrength condition of the Army of Northern Virginia. Robert E. Lee had commanded nearly 90,000 men in it when he assumed command of the army in June, but the Seven Days Battles cost him 20,000 casualties and the northern Virginia campaign another 12,000 or so. Along with the marching into Maryland, the manpower of the army dropped even more due to straggling, lack of food, and a significant number of soldiers in Virginia regiments deserting on the grounds that they had signed up to defend their state and not invade the North. Significant numbers of Confederate soldiers had no shoes and were unable to handle the macadamized roads of Maryland. Lee may have had under 40,000 men on the field at Antietam, the smallest and most ragged his army would be until the final days of the Petersburg Siege. Many brigades were the size of regiments, their regiments company-sized. Despite the ragged condition of the army, morale was high and almost all of the Confederates were veterans, which put them at an advantage over the numerous green Union regiments. The divisions of McLaws and D.H. Hill had been left in the Richmond area during the northern Virginia campaign; they quickly rejoined the army for the march into Maryland. Lee was also reinforced by Brig. Gen John G. Walker's two-brigade division from North Carolina. The exact size of the Army of Northern Virginia at Antietam has been a source of debate since the 19th century since no army returns were made between July 20 and September 22. "Lost Cause" propagandists during the postwar years presented a picture of Lee being severely understrength and possibly having as few as 30,000 men on the field. Union generals and veterans of the war generally believed that the Army of Northern Virginia was not that small on September 17, and estimated Confederate strength as high as 50,000 men. It seems almost certain that the most exhausted and understrength Confederate divisions were Lawton's and the Stonewall Division, as both had been fighting and marching since May almost without a break. Other Confederate divisions such as D.H. Hill's, had not fought since the Peninsula