 Meanwhile , the Union artillery fire was planned and directed nearly flawlessly . As historian Jennings Cropper Wise notes , Col. Hunt , McClellan 's chief of artillery , continuously refocused Union fire on various fronts , in an " enormous sheaf of fire of more than 50 superior pieces , disabling four of Huger 's and several of Jackson 's batteries almost the instant they came into action " . This severely hampered the Confederates ' ability to respond effectively to the Federal barrage . The Union artillery subdued a number of the Southerners ' batteries ; those few that remained attacked piecemeal , and failed to produce any significant result . 
