Before the development of explosives , sapping was the undermining of an enemy 's fortifications , which would collapse when the sap 's supports were removed . Later , explosives were placed surreptitiously in the undermining sap or mine , then detonated , as was done with 450 tons of high explosive in the First World War battle of Messines , the largest planned explosion until the 1945 Trinity atomic bomb test
Trinity atomic bomb test
Trinity (nuclear test)
Sapping