By nightfall, the Confederate Second Corps had advanced more than 1.25 miles, to within sight of Chancellorsville, but darkness and confusion were taking their toll. The attackers were almost as disorganized as the routed defenders. Although the XI Corps had been defeated, it had retained some coherence as a unit. The corps suffered nearly 2,500 casualties (259 killed, 1,173 wounded, and 994 missing or captured), about one quarter of its strength, including 12 of 23 regimental commanders, which suggests that they fought fiercely during their retreat.^[12]

Jackson's force was now separated from Lee's men only by Sickles's corps, which had been separated from the main body of the army after its foray attacking Jackson's column earlier in the afternoon. Like everyone else in the Union army, the III Corps had been unaware of Jackson's attack. When he first heard the news, Sickles was skeptical, but finally believed it and decided to pull back to Hazel Grove.^[12]