During the siege of Petersburg, Union troops who had been coal miners before the War convinced the Union Command that they could dig a mine beneath the Confederate works, load it with explosives and blow a hole in the Confederate lines. This would be followed by a frontal charge through the gap and a Union victory.
The first few steps of the plan worked and the explosion sent men, artillery, dirt and debris into the air. In one of the classic command blunders of the War untrained men were sent into the Crater left by the explosion. Instead of moving forward they stopped to gape at the carnage. Confederate troops did not hesitate in shutting the gap in their lines and rushed to the Crater. Union troops were helpless and easy targets. Casualties on the Union side were over 5,000 men. Confederate losses were minimal. Grant decided to stop any further frontal charges and the Siege of Petersburg went on for many more months.