In late June 1864, Lieutenant Colonel Henry Pleasants submitted an idea to the Ninth Corps leader, General Burnside, to tunnel under the enemy position and blow it up with gunpowder. The proposal was to dig a mine to the opposing Confederate trenches, a distance of about 511 feet.

Burnside submitted the plan to his superiors, and Grant and Meade allowed the construction of the tunnel to begin, though they were skeptical whether the plan would work. Despite Grant and Meade's reservations, coal miners in Burnside's corps began work immediately.