Being
the stronghold where the troops station, passes are often located
in the key position of the wall, to get the effect of "if
one man guards the pass, tens of thousand never want to get through".
Generally speaking, the pass is composed of a city wall (square
or polygon shaped), city gate, gate tower, luocheng, wengcheng
(the following paragraphs will further explain these two fortifications),
and moat.
City
wall: It is the main component of the pass, often measures
about 33 feet tall. The outside of the wall was laid by pieces
of large bricks or stones with the inner comprising of yellow
earth and debris. The top of the wall measures about 4.4 to 5.5
yards which enables four horses to run side by side. On the wall,
there are forts from where soldiers can overlook and shoot with
low parapets (Nuqiang in Chinese) to protect people and horses
in case they fell over the wall.
City gate: In peacetime, it is the passageway
for soldiers passing in and out. At war, it is used for the exit
to counter attack enemies. Many gates are carved the name of the
pass. Inside the opening, a pair of wooden doors stand there which
are covered by sheet iron on the outside. The inner sides of the
doors are secured by big bolts and lock holes. Even machineries
are hidden inside to kill the intruders.
Gate
tower: It has one, two or three floors and usually made
of wood or bricks. It is stands on top of the gate and serves
as a watch tower and commanding post when war is imminent. Many
gate towers are colorfully painted and intricately decorated,
which makes them look like delicate artwork. The gate tower of
Shanhaiguan
Pass is a typical example of this.
Wengcheng: A small enclosure which is built
on the outer side of the wall. It serves as another line of the
city wall to strengthen the defensibility of the city gate.
Luocheng: It is a secondary wall built to protect
the Wengcheng which is often the main target of enemies. On the
top, there are also towers to watch the enemy's situation and
command battlement.
Moat: There is usually a moat around the pass.
It is a deep trench filled with water after excavation to build
the pass. Being another line of defense, it increases the difficulty
for enemies to attack the city and creates opportunities for soldiers
on the wall to attack intruders.