Along the road running from North to
South Vietnam, nowadays there have remained only two feudal
citadels, one in Hue and the other in Dien Khanh.
Dien Khanh Castle was modelled on Vauban's invention of
fortifications which were well known to European strategists in
the 17th and 18th centuries. It had an area
of about 36,000 sq.m, the wall of the rampart was was 2,693m long
and 3.5m high. This was along structure of earth, hexagonal in
shape.
The exterior of the rampart was almost erect, the interior was
rather sloping with two stages providing easy communication and
transport.
The rampart was designed with many curved sections instead of the
conventional protruding parts so as to province more convenience
for surveilance. The corners of the rampart were spacious enough
for troop deployments and had each a small fortress 2m high with a
heavy gun mounted. Along the wall there were hedges of bamboo and
thorn plants. Below the exterior wall there were moats 3 - 5m
deep, 15 - 40m wide, with water supplied by the river Cai. A small
road built for patrols surrounded the wall, it was called the "
road of surveilance".
