 In the course of four hours , a series of blunders in planning and communication had caused Lee 's forces to launch three failed frontal infantry assaults across hundreds of yards of open ground , unsupported by Confederate artillery , charging toward firmly entrenched Union infantry and artillery defenses . These errors provided Union forces with an opportunity to inflict heavy casualties . In the aftermath of the battle , however , the Confederate press heralded Lee as the savior of Richmond . In stark contrast , McClellan was accused of being absent from the battlefield , a harsh criticism that haunted him when he ran for president in 1864 . 
