page_title: Pencil detonator
section_title: Usage
hierarchical_section_title: Pencil detonator / Usage
caption_attribution_description: Deutsch: Chemischer Bleistift-Zeitzünder des Anschlags vom 20.&#160;Juli 1944 Exponat im Militärhistorischen Museum der Bundeswehr in Dresden
context_page_description: A pencil detonator or time pencil is a time fuze designed to be connected to a detonator or short length of safety fuse. They are about the same size and shape as a pencil, hence the name. They were introduced during World War II and developed at Aston House, Hertfordshire, UK.
context_section_description: For very high-value targets it is recommended that two pencil detonators from different batches be used together. That way if one detonator fails the other will almost surely blow the charge. Note that if both detonators were going to work, the explosion will occur at the minimum of the two times; thus this method will also slightly reduce the average delay.
  Pencil detonators saw heavy use during the Second World War by the Special Air Service, Special Operations Executive and groups such as the French Resistance. A number of pencil detonators were used to detonate the massive amatol charge hidden inside HMS Campbeltown during the St Nazaire Raid of 1942. The ship exploded over an hour later than anticipated.
  Approximately 12 million pencil detonators were produced in Britain during the war. However, in recent years they have been superseded by electronic timers which are more accurate and provide much longer delay times.
  The briefcase bomb used in the July 20 plot used a captured British pencil detonator inserted into a block of British plastic explosives weighing approximately two pounds. The bomb was set to 30 minutes and detonated as planned, but Hitler survived with minor injuries. Stauffenberg could not prepare the second block, though. He got rid of it while driving through the forest to the airfield. His driver, Leutnant Erich Kretz, reported seeing Werner von Haeften throw something into the woods in his mirror.
caption: Pencil detonator used in the July 20 plot in 1944 exhibitied in Militärhistorisches Museum der Bundeswehr in Dresden (Germany)
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