What caused the Union's tunnel into Petersburg to fail?

Answer 1

In July of 1864, the Confederate city of Petersburg was placed under siege by General Grant's forces. It would be a ten month siege and began following the Union's defeat at the Battle of Cold Harbor. In an attempt to capture the heavily fortified Petersburg, a Union regiment composed mainly of coalminers who were familiar with explosives came upon what seemed to be an ingenious plan.

They set about digging a tunnel underneath Confederate entrenchments and planted enough gun powder to destroy the fortifications and blow up any Confederate soldiers in the way.

On July 30, 1864 a huge explosion took place underneath Rebel lines that created a crater 170 feet long, 30 feet deep and 70 feet wide.

Four hours passed and nothing happened. Somehow and whose command is not known, the Union soldiers decided to charge into the tunnel the explosion created.

Confederate forces were stunned of course but as they gathered their wits, they shot the Union intruders one by one as they exited the tunnel on Rebel territory. The result was 4,000 Union casualties and 1,500 Confederate casualties before Union officers called for a retreat.