These trenches were possibly dug as a result of the Boer war, to find ways for artillery to destroy them.
Regardless of why they were dug, they are undoubtedly old.
Please Note: This is a Military Training Area on which live firing and other pyrotechnics may be used. The area is generally open public access. One of the safety rules for public access is:- Do not, (and ensure that children do not) approach, touch or pick up any metal objects lying on the ground. Please obey all byelaws and locally posted information concerning times when the area may be closed. These may be physical barriers, flags or lights.
This cache complies with the DNPA agreement for geocaching - http://www.dartmoor-npa.gov.uk/visiting/vi-enjoyingdartmoor/geocaching