The Battle of the Crater was the American Civil War's biggest waste of life. Unionists attacked Confederate lines during the Siege of Petersburg in 1864. They dug a 511-foot tunnel under the Confederates and loaded it with 8000 pounds of gunpowder. They blew up hundreds of Confederate soldiers and created a massive crater. The Union's leadership made colossal errors. They poured troops into the crater instead of flanking the stricken Confederates. The Confederates regrouped and trapped the Union