The massive crater at <a href="https://en.wikipedia.org/wiki/Petersburg,_Virginia" class="extiw" title="w:Petersburg, Virginia">Petersburg</a> made by an explosion from underneath Confederate entrenchments on July 30, 1864.
Unknown author<span style="display: none;">Unknown author</span>
File from <i><a rel="nofollow" class="external text" href="https://archive.org/stream/photographichist03mill#page/193/mode/1up">The Photographic History of The Civil War in Ten Volumes: Volume Three, The Decisive Battles</a></i>. The Review of Reviews Co., New York. 1911. p. 193.