Battle of the Crater. Petersburg, Virginia. Two bluecoats, former miners, suggest digging a tunnel beneath the Confederate lines and blowing them up with a massive dynamite charge. The excavation work, a complex engineering feat for the time and under enemy fire, begins on June 25th and ends on July 23rd with several innovations to lengthen the fuse while maintaining reliability, to ventilate the tunnel, and so on. Finally, the mine is detonated just beneath enemy lines as planned, shattering the front at one point with a crater measuring 50m x 30m and 10m deep. The Confederates attack, but too many men are tied up in a narrow corridor, and the Confederates have time to recover and halt the advance right inside the crater, where they massacre 3,700 bluecoats, killed and wounded. The grays lose 1,500 men.
