That artillery piece was a thirty-pounder Parrott rifle with an iron barrel more than eleven feet long and weighing nearly two tons. The gun’s metal-rimmed wheels stood as high as a man’s shoulders, and the huge weapon had needed nineteen horses to drag it forward during the last hours of darkness. Indeed its slow progress had held up the advance of the whole federal army, and some northern officers thought it madness to maneuver such a giant piece of fortress artillery into the army’s forwardmost positions, but every soldier who saw the cumbersome gun roll ponderously past in the first light of dawn reckoned that the beast would be a battle winner all by itself. The bore of the rifled barrel was over four inches across, while its iron-banded black breech was now crammed with nearly four pounds of black powder onto which a conical shell had been rammed. The shell was filled with black powder and was designed to burst apart in a killing explosion of flame and shattering iron that would tear and splinter and flense the rebels on the Bull Run’s far bank, though presently the dawn’s early light was hardly revealing much in the way of targets on that rebel side of the stream. Once in a while a Confederate officer spurred a horse across a distant field, and some few infantrymen were scattered on a hill that lay at least a mile beyond the stone bridge, but otherwise there was small evidence that the rebels were present in any force.

A friction primer was shoved through the Parrott’s touchhole and deep into the canvas bag of black powder. The primer was a copper tube filled with finely mealed gunpowder. The topmost section of the tube held a small charge of fulminate and was pierced by a serrated metal crosspiece, which when pulled hard by its lanyard would scrape violently across the fulminate and, just like a match head scratched by a file, would detonate the fulminate with friction. A gunner sergeant now grabbed the lanyard’s free end while the other crew members stood well clear of the weapon’s lethal recoil.

“Ready!” the gunner sergeant called. Some of the crewmen from the other guns in the battery had assembled in a small group to listen to a Bible reading and to say a prayer, but all now turned toward the giant Parrott rifle and covered their ears.