After Bull Run, the northern armies retreated to the defenses of Washington, DC, to reorganize, train, and equip for a protracted war. Governor Morgan continued to send new regiments into the fight, and New York's industries developed their technological capabilities and produced more sophisticated weapons for the battlefield.
Both sides gained combat experience and developed new, skilled leaders. Casualties rose even as battles remained indecisive. Confederates shifted from their defensive strategy and invaded Maryland hoping to turn public sentiment against the war effort.