09/28/2026
Modern technology can be amazing!
📌 British Fortifications — Yorktown, Virginia
📍 37°14'08.68"N 76°30'38.70"W
Few places in America show the mechanics of an 18th-century siege as clearly in LiDAR as Yorktown.
In the fall of 1781, roughly 17,600 American and French troops converged on Yorktown, trapping about 8,300 British and allied troops under Lt. Gen. Charles Cornwallis against the York River. Cornwallis had fortified the town with a network of redoubts, artillery batteries, trenches, and connecting earthworks, while a second British position held Gloucester Point across the river. George Washington and French commander the Comte de Rochambeau began investing Yorktown on September 28, and Cornwallis abandoned several outer positions the following day, letting the allies tighten the noose around the British defenses.
Then came the enormous engineering operation that's still written across this landscape. On the night of October 6, American and French soldiers began digging the First Parallel, an extensive siege trench roughly 800 yards from the British inner defenses. Artillery batteries went up along the line, and on October 9 the bombardment began, Washington himself fired the first American gun that evening, while French batteries joined in pounding Yorktown and British shipping in the river.
But Washington wanted his artillery closer. On October 11, Allied troops began digging the Second Parallel, pushing the siege works nearer the British defenses, with two detached British strongpoints, Redoubts 9 and 10, standing in the way of completing the line. On the night of October 14, both were attacked. About 400 French troops stormed Redoubt No. 9, while an American force led by Alexander Hamilton attacked Redoubt No. 10. Both fell, and the captured redoubts were incorporated directly into the Second Parallel, letting the Allies push their artillery to within point-blank range of Cornwallis's defenses.
By October 16–17, the Allied bombardment was devastating the British position. Cornwallis tried to evacuate his army across the York to Gloucester Point, but the effort failed. Negotiations followed, and on October 19, 1781, Cornwallis's army surrendered, a victory that effectively ended major combat in the American Revolution and dealt a decisive blow to Britain's effort to hold onto its American colonies.
There's something important to understand when looking at this LiDAR, though: not every earthwork visible here is untouched from 1781. Washington ordered portions of the Allied siege works destroyed after the victory so they couldn't later be used against French troops occupying Yorktown. Eighty years later, Confederate forces returned to this same terrain and modified surviving British Revolutionary War defenses during the 1862 Peninsula Campaign, while Union forces built additional siege works through portions of Washington's former encampment areas. Then, during the 1930s, the National Park Service reconstructed portions of the American and French siege lines using archaeological evidence and surviving military maps. So the landscape visible today, and in LiDAR, is really a combination of surviving historic terrain, Revolutionary War earthworks, later Civil War alterations, and reconstructed sections of the 1781 siege lines.
That layered history is exactly what makes the LiDAR here so fascinating. Modern aerial photography shows Yorktown's roads, buildings, forests, and National Park Service landscape. Strip away the vegetation with LiDAR, and an entirely different Yorktown emerges, angular forts, redoubts, batteries, trenches, and long defensive lines stretching across terrain where Washington, Rochambeau, and Cornwallis fought out one of the most consequential military operations in American history.
More than two centuries later, the geometry of the siege is still written across the ground.
