A Surprise discovery has been unearthed on the lower Lines where they are building a new campus for Mid kent College.
A series of Tunnels were already known about on the site but now they have uncovered a small domed shape structure that looks like an igloo.
Archaeologists from Canterbury Archaeological Trust have comfirmed it is a Listening post used to listen for possible enemy Sapping activity(Tunnel digging)
During a Siege on the fortifications the Attacking Army would dig a Trench Parrallel to the Fortifications for cover.Then they would dig Zig-zag Trenches towards the Fortifications and dig another Parrallel Trench.They would do this several more times untill they were close enough to the Fortifications to Dig a Siege Tunnel under the Dry Ditches and then use explosives to blow up the Dry Ditch walls and to breach the Fortifications.
Meanwhile the defending Army would be listening for possible Tunnel activity with the listening post.If enemy Tunneling activity was heard nearby they would have been able to dig a Countermine then when they were close enough blow up their own Tunnel and destroy the Enemy Tunnel.
The Listening Post is thought to date from the Early 1800's
More info on Sapping: http://www.remuseum.org.uk/corpshistory/rem_corps_sapper.htm
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