Poliorcetic Photography: Bastion Atlanta

Good engineering is timeless

One of my projects in the coming months is a broader assessment of the union artillery advantage in the American Civil War. Primary sources from the confederate side agree that in the battles of the west, Gen. Ulysses Grant enjoyed a decisive firepower advantage that made rebel position after position untenable. Much of this fire support floated on river gunboats, particularly ironclads, for which the south had no answer. Having fewer roads and rails than the north, southerners depended far more on the riverine connections that were so vulnerable to these union gunboats. Muscle Shoals and Vicksburg were the last points of resistance on the Tennessee and Mississippi simply because they lay on prominent bluffs high over the water. In the days before rapid, elevated, indirect artillery fire, that bit of altitude was just enough to nullify this crucial, floating artillery advantage that the union side enjoyed.

I will write more about all this soon enough. Today, let’s just focus on the defenses of Atlanta, because they are a study in the possibilities of earlier times. Don’t get me wrong, I am not claiming that this photo of Confederate defenses guarding Peachtree Street is a 1:1 replacement of, say, a Prussian earthwork bastion during the late Seven Years’ War. Rather, the idea of defensive artillery strongpoints, consisting of dirt ramparts with various wooden or fibrous reinforcement, was quite ancient in 1864. One might argue that it has always existed.

So if we used Photoshop to lay the foreground image from Atlanta on top of a 17th Century London skyline, it would probably not be far off from what travel writer William Lithgow described during the English Civil War as he toured the defenses of London. Indeed, he makes detailed description of artillery platforms like the ones you see in the photo. These help prevent the guns from getting stuck in muddy holes or ruts and also provide a firm, safe surface for crew drill. Protected from the flat-trajectory cannonballs aimed at them by enemy gun crews, defenders can dominate their respective fire lanes with ball, grape, or chain shot. Two of these positions with interlocking fire lanes will pulverize any frontal assault. You can only take a position like this by maneuver, as Gen. William Tecumseh Sherman did. Using classic Frederician tactics, his entire campaign for Atlanta was a series of outflanking movements that dislodged the Confederacy from one defensive position after another, and finally from the city itself, without a battle of the scale of Gettysburg.

Gen. John B. Hood simply lacked the wherewithal to maintain lines of resistance and extend them indefinitely. Sherman knew it. He could win by relentlessly pressing the southern shortcomings in numbers, weapons, and logistics at its flanks. This was attritional doctrine, and it is always present in siegecraft. So is engineering. If I could time-travel, I would go pick up Charles VIII’s master gunner in 1494, whisk him to English Civil War London and then American Civil War Atlanta, and ask him what the similarities and differences with his own siegeworks are. No doubt there would be plenty of both.

Late Medieval Poliorcetic Art