09/28/2026
📌 Fort Davis — Petersburg, Virginia
📍 37°11'33.65"N 77°22'29.97"W
A Union soldier summed up this fort's design in one sentence: "square with a diagonal through it." More than 160 years later, that diagonal is still sitting right there in the LiDAR.
Fort Davis is one of those places where LiDAR and an original engineering plan line up almost perfectly. After the Union Army failed to take Petersburg by direct assault in June 1864, Ulysses S. Grant began extending his lines south and west to cut the railroads supplying Robert E. Lee's army and Richmond. During the fighting along the Jerusalem Plank Road, June 21–23, Union forces pushed their trench system across the road but fell short of severing the Petersburg and Weldon Railroad. To protect that newly gained ground, soldiers began building a substantial enclosed earthwork, initially called Fort Warren after Fifth Corps commander Maj. Gen. Gouverneur K. Warren.
The scale of the work is impressive. According to the historical marker at the fort, the work covered roughly three acres, with soldiers excavating a ditch about 20 feet wide and 10 feet deep and throwing the earth inward to form a rampart another 10 feet high. The finished fort could hold approximately 550 soldiers and eight field guns, with a magazine and two wells. The unusual interior traverses visible in the historical plan were substantial defensive features, intended in part to limit the effects of artillery fire inside the fort.
Its name changed only weeks after construction began. On July 11, 1864, Col. P. Stearns Davis of the 39th Massachusetts Infantry was mortally wounded nearby by a fragment from an exploding artillery shell, and the fort was renamed Fort Davis in his honor. The National Park Service still lists Davis among the officers commemorated by the named Union forts surrounding Petersburg.
Fort Davis became one strongpoint in an increasingly enormous Union siege system. As Grant kept moving west, more forts and batteries went up, all connected by miles of trenches. The wartime map puts that in perspective: Davis was just one link in a chain that eventually included Forts Sedgwick, Rice, Meikle, Morton, Haskell, and Stedman to the northeast, and Forts Alexander Hays, Howard, Wadsworth, Dushane, and many others extending west. The siege continued until the fall of Petersburg on April 2, 1865.
What makes Fort Davis especially interesting for LiDAR is its preservation. Modern development has nearly swallowed the position, with roads, businesses, parking lots, and neighborhoods now surrounding this little island of Civil War terrain, and from ordinary aerial imagery, the fort is surprisingly easy to overlook.
LiDAR tells a completely different story. The enormous square perimeter, deep exterior ditch, and distinctive diagonal interior traverses jump right out of the landscape. Better still, overlaying the historic engineering plan directly onto the LiDAR shows how much of the original geometry survives, the ramparts, corners, ditch, and major interior works correspond remarkably well with what Union engineers laid out more than 160 years ago.
The city has grown up around Fort Davis, but the fort itself remains unmistakable. Remove the trees with LiDAR, and the engineering of the Siege of Petersburg is still sitting right there in the middle of the modern city.
