"We shall be in the ditch of the enemies works by tomorrow night or early morning; and the powder is wanting to blow up the works. I beg you will send the powder the moment this reaches you."
—General Nathanael Greene to General Andrew Pickens, June 11, 1781
The Patriots were in striking distance of the fort walls and Col. Kosciuzko decided to use another classic siege tactic—a mine. The plan was simple. Gunpowder packed in the mine's primary tunnel would be detonated, causing a breach, which would allow Greene's men to rush into the fort from nearby approach trenches. Using picks and shovels to carve out the hard earth, laborers began to dig the main shaft on June 9. Progress in the late spring heat and under constant Loyalist fire was painfully slow. The Star Fort siege ended before Kosciuszko's mine could prove its worth. Learning that the Loyalists were getting reinforcements, Greene called off the effort, and digging stopped short of the fort's ditch. The cone-shaped earthen passage, with no beams or supports, which runs 125 feet from end to end, is a unique example of Revolutionary War-era mine construction. The mine is one of the few remaining earthworks of the Revolutionary War. It is not accessible to visitors.