The beginnings of the
American Internal Border, or simply
The Border, were laid even before the war officially ended. The ceasefire declared on May 11th 1870 all but solidified the battlelines that scarred the landscape. In the waning days of the Civil War, the states themselves were divided between the forces of the North and the forces of the South. Nowhere the division was more stark, than in Pennsylvania. Occupied for the majority of the war and ravaged by devastating battles at its largest cities, the state was split in two. In occupied Pennsylvania, rebel activity was met with harsh reprisals; anyone suspected of supporting them were driven from their homes. Most returned after rebel forces retook most of the state, but in the territory that the Republic continued to control, their leave turned out to be permanent.
The ceasefire was declared after an arduous stalemate through the work of the Ohio Foreign Department. Few thought that the current map would last for long at first, until the two sides attempted to negotiate an armistice agreement. For nearly two months, delegations from the north and south haggled in Harrisonburg, over nearly all parts of the agreement, especially over the exchange of prisoners of war. It was only until the timely threat of Ohio intervention that the South would agree to the terms. From then on, few would believe that a formal peace treaty would ever be signed. And they would be right.
The Harrisonburg Armistice never explicitly established a demilitarized zone along the border. Instead it was an unintended consequence of a stalemate frozen in mid battle. Even before the ceasefire was declared, the frontline was stagnant for months as both sides. Basic earthworks were more than enough to repel the attacks of disorganized militia forces. When the ceasefire was declared in May, both sides took the opportunity to upgrade their defences in case. The uneasy ceasefire would largely remain untested until it was clear that a comprehensive peace treaty would never be signed. Then things really got tense.
In the months that followed, border incidents occurred almost weekly. Troops stationed at their significantly improved fortifications, would often open fire with muskets and the occasional cannon over any perceived provocation. While neither side trusted each other and fully expected a war at some point in the future, no one wanted another war at that moment. Tensions would slowly deescalate over time as professional trained troops with significantly better trigger discipline replaced the ragtag militias that had manned the trenches. Meanwhile their hastily constructed basic trenches were expanded upon and eventually replaced with larger wallsand elevated gun platforms, just out of range of enemy guns.
By the end of 1871, the North-South border was firmly established as the most militarized border on the entire continent. Along the entire stretch of the North-South border from the Ohio River in the west to Delaware Bay in the east, thousands of soldiers manned a complex system of walls, forts, artillery positions, and trenches facing their counterparts across the border. While the majority of the fortifications consisted of small walls and trenches, dozens of major forts were constructed along the border especially in the east. Between the lines was an effective no man's land, forbidden to large troop formations by agreement. The majority of the troops would remain in the hinterlands behind their border at military bases, ready to rush to the border to repel an invasion at a moment’s notice. As a peace deal was never signed, the war never truly ended and the troops that manned both fortifications were technically still in a state of war. However only major border skirmishes would occur; the majority resulting from escaping slaves crossing the Internal Border. Large-scale warfare would only resume with the beginning of the Great Crusade nearly 40 years later.