From the Richmond Sentinel, 10/1/1863, p. 1, c. 6
Attempt to Mine Out. – Struck with the amazing facility with which some of our best defences have been mined out of existence as Confederate strongholds, sundry prisoners in Castle Thunder have recently undertaken to secure escape by a similar process. Examinations of the premises on yesterday developed sundry “saps” under the walls of the stable, which had evidently been in progress for several days. – They were not completed. The diggers had masked their operations by a convenient pile of rocks which shut off casual observation, and would have protected them from a fire in the rear had they been caught in flagrante delicto.