Single Entrance Souterrains

Sherlock Holmes once remarked 'You see, but you do not observe.' In examining any site, the archaeologist must pick up on clues hidden in plain sight. For souterrains, the principle of 'Form follows Function' allows the evidence to be found. By examining the form of a souterrian we can deduce the function.

Large 'single entrance' souterrains were discovered at Newtownbalregan (45m long) and Tateetra (70m long). Both these souterrains were placed outside the nearby settlement. Single-entrance souterrains usually have three zones:

Storage Zone
Both Newtownbalregan and Tateetra had day-to-day storage areas at the entrance.

Security Zone
Newtownbalregan and Tateetra had strong internal doors within their zig-zag security zones. These doors were double braced with horizontal beams fitting into the souterrain walls. Each also had a drophole creep which could have been stoppered in an emergency. These arrangements would confound any attempts to smoke out the occupants and created constrictions with murderous opportunities.

Hideaway zone
The back of these souterrains had a large passage and chamber where people could retreat.

ASI: Didn't the air run out underground?
Air was drawn into large souterrains through dedicated shafts. Big souterrains were placed on a slight slope so air was drawn into the hideaway zone, passed through the security zone, and emerged at the entrance. Unfortunately this slope also allowed water to drain into the souterrain and collect in the lower chambers. Newtownbalregan was flooded when found and Tateetra had numerous drainage sumps dug into the floors.

ASI: You go in first
A souterrain is an effective hideaway. The entrance is usually hidden, either in a building or in deep undergrowth. Souterrains zig-zag so raiders cannot predict where to dig anyone out and the zig-zags prevent arrows being fired down them. With a supply of air, food and water the occupants can stay down for several days.

The souterrain favours defenders who retreat backwards into the structure. The small space means only one person can meet another head-on. Many of the traps in a souterrain mean someone waiting inside can attack whoever is coming through. If a raider or defender is wounded then his body is an added obstruction.