Lochnagar Mine was a pile of explosives dug under the German front lines in France by the British during WWI. This was of course during the era of trench warfare, one of the most spectacularly futile endeavors in human history, with the consequence that the Brits dug a chamber fifty feet beneath German lines and filled it with 60,000 pounds of ammonal (ammonium nitrate and aluminum powder) explosive. On July 1, 1916 the explosives were detonated creating a crater about 100 feet deep and 300 feet in diameter.
Considering that the war dragged on for another two and a half years… all that effort and destruction, for nothing. And in the end, the allies set up a punitive system that virtually ensured that something worse would come along… and of course it did.