July 1864. Grant's siege of Petersburg is at a standstill. A Federal regiment made up mostly of Pennsylvania coal miners, under the command of Lt. Colonel Henry Pleasants, secures the reluctant approval of Generals Meade and, ultimately, Grant to pursue an outrageous strategy: tunnel under the Confederate trenches, and blow up the Confederate troops. The 586-foot tunnel is completed in a month. Four tons of powder explode in a devastating surprise...