There used to be a show called Danger UXB which told the story of the bomb defusers in the UK fighting the legacy of World War II. But here’s an interesting piece from the German side of things, published today in Der Spiegel.
In the whole of Germany, more than 2,000 tons of American and British aerial bombs and all sorts of munitions ranging from German hand grenades and tank mines to Russian artillery shells are recovered each year.
Kind of interesting is the reason some didn’t go off. Soil conditions and gravity prevented some of the chemical triggers from activating 60 years ago.
An estimated 20,000 delay-action bombs were dropped on Oranienburg during the war because it had a suspected atomic bomb research site, the Heinkel aircraft factory and a pharmaceutical plant. They were designed to explode between two and 146 hours after hitting the ground, to disrupt clearing up work and cause chaos.
But many failed to go off because Oranienburg has soft soil with a hard layer of gravel underneath. That meant bombs would penetrate the earth, bounce off the gravel and come to rest underground with their tips pointing back upwards. In that position gravity stops the chemical detonators from working. They contain a vial of acetone which bursts on impact and is meant to trickle down and dissolve a celluloid disk that keeps back the cocked firing pin.
But when the bomb is pointed upwards, the acetone seeps away from the celluloid, leaving only the vapors to wear the disk down.