“Battle of the Crater” where Union troops undermined a section of Confederate lines and detonated a large amount of gunpowder blowing a large crater in the lines. The main cause of failure to exploit the situation was that the “Colored” troops that were trained to go around the crater and push on through the Confederate lines were replaced at the last minute with untrained White troops because some commanders didn’t think the “Colored” troops were unto the job. The replacement assault troops, instead of going around the crater went into it and got bogged down giving Lee time to bring up reinforcements and stop the assault.
Another thing that got blown up was Burnside’s military career. They finally got rid of him, after all the damage he did.