This immense fire-power (in a confined space) made a killing field of the redoubt. Those Union attackers that managed to survive the attack across open-ground had to climb a 18-foot breastwork (including trench) before even getting to grips with the defenders – who simply stuck the muskets out of fire-holes and opened-fire at point-blank range! On top of this, Confederate “Grenadiers” lobbed cannon-balls with five-second fuses into the mass of attacking enemy troops. Needless to say, bravery has its limit, and many Union soldiers broke-off the attack and retreated back to their lines – usually minus copious numbers of their friends and colleagues. Meanwhile, Confederate casualties were minimal.