In their routine patrol of the James River, the squadron was surprised to discover, on the morning of October 22, that the Union Army had finished fortifying Cox Hill. To cover the retreat of the Confederate wooden vessels, "Virginia II" approached the battery, followed by two ironclads, and effected a retreat upstream to Chaffin's Bluff. During this, the "Virginia II"s smokestack was riddled by shells. Though caught by surprise, this small action helped determine the effectiveness of the ironclads' armored casemates against close rifled cannon fire, and in the case of the "Virginia II", the results were favorable: her casemate withstood 7 direct hits by 100-pound conical iron "bolts," which barely dented her plating.