Chinese fortification: an overview of parts and terminology — Part 2: Gate and moat

UPDATED JUNE 10, 2024

2) The gate

The second part of this series will provide an overview on various components of Chinese gate, as well as their names. As before, italicised names are likely modern terminology.

2.1) Cheng Men (城門, lit. 'Wall gate')

As with all fortifications around the world, the gate is the most vulnerable—and often the most heavily fortified—part of a Chinese city. The Chinese term Cheng Men can refer to both the gate door itself, as well as the gatehouse securing the entrance. For clarity's sake I will separate gatehouse, gateway tunnel, and gate doors into three sections.

Gatehouse

Zhonghua Gatehouse of the city wall of Nanjing.

The term "gatehouse" is actually a misnomer, as a typical Chinese gatehouse is a relatively featureless block of rammed earth and bricks, with one or several gateways tunnelled through it. Most of the defensive features of a Chinese gatehouse are taken up by the guard tower built on top of it.

One notable difference between Chinese and European castle gatehouse design is that flanking towers were rarely used by Chinese people to bolster the defence of their gatehouses. This is largely due to the fact that the primary function of flanking towers can be better fulfilled by Weng Cheng, although that is not to say flanking towers were never used.

The gate of Jimingyi fortified postal/relay station is a rare example of a Chinese gatehouse with prominent flanking bastions.

Gateway tunnel

Early Chinese gateway tunnels were trapezoidal in shape and used wooden columns and lintels to support the structural integrity of the entire tunnel. However, such design was extremely vulnerable to fire, so it was quickly superseded by the more robust arched tunnel as soon as Chinese people figured out how to build a stone arch. As such, most surviving Chinese city gates today have arched tunnels.

Section of the Song-period painting "Along the River During the Qingming Festival", depicting a trapezoid gateway. 

Owing to its large size, a Chinese gatehouse has fairly deep gateway tunnel. Gate doors are usually (but not always) placed deep inside the tunnel to protect them against the elements as well as indirect fire artillery. However, if the enemy managed to get into the tunnel and start battering down the doors, there's little can be done by the defenders on the wall to force them out. To mitigate this issue, gateway tunnels of larger gatehouses typically come with smaller branch tunnels that connect to Cang Bing Dong (藏兵洞).

Cang Bing Dong inside the gateway tunnel of Zhonghua Gate.

Gate doors

Despite its rather inconspicuous appearance in comparison to the massive walls and majestic towers, Chinese gate door is actually incredibly sophisticated and complex.

Front (left) and back (right) side of Chinese doors, Forbidden City.

A typical Chinese gate door is a heavy wooden door, almost always rectangular in shape, and of the Shi Ta Men (實榻門, lit. 'Solid-bed door') type construction. Outwardly, it is not too dissimilar to a typical ledged door. However, instead of simply securing the ledges to the boards by means of nails and metal bracing, the ledges of a Chinese door are directly slotted into the boards with sliding dovetail joints and secured from the sides with mortice and tenon joints, which make for a very strong door. Due to its large size, Chinese gate door is not hinged to a frame, instead it is built as pivot door.

Ledges of a Chinese gate door are usually reinforced with metal door nails from the side facing outward. Door nails found on ornate or important gate doors (such as the gate doors of Forbidden City) tend to have enormous dome-shaped caps (some nail caps can be as large as, or even larger than, the fist of an adult male), said to help in retaining the mud used to fireproof the doors. Smaller and more utilitarian gate doors (such as the gate doors of Shanhai Pass) have sensibly-sized door nails, however.

Two gilded door nails.

From Song Dynasty onward, most Chinese gate doors were further reinforced with heavy iron plating, although precious few of these reinforced doors survive to the present.

Surviving Qing period doors of Chengen Gate of Taipei, with still-visible iron plates on the top portion of the doors.

Que (闕)

Que "wings" of the Meridian Gate of the Forbidden City.

Also known as Que Men (闕門) and very rarely Guan (觀), Que refers to a type of ancient ceremonial gate tower commonly found at the gateways of palaces, temples, tombs and bridges. Originally built as free-standing towers, by later period Que towers were usually fused into the gatehouse building to form a single U-shaped structure.

The number of Que tower may change depending on the symbolic significance and prestige of its associated building. Most forms of Que towers only have two single towers—one on each side, while Que towers used by nobilities or high ranking government officials, known as Er Chu Que (二出闕) or Mu Zi Que (母子闕, lit. 'Mother-and-son Que'), have two adjoining towers on each side. The most prestigious version reserved for the emperor, known as San Chu Que (三出闕), have three adjoining towers on each side.

2.2) Gatehouse facilities

Cha Ban (插版, lit. 'Slotting plank')

A Cha Ban half-concealed inside the groove of a gateway tunnel. Gonghua Fortress, Beijing.

More properly known as Zha Ban (閘板, lit. 'Floodgate plank'), Gan Ge Ban (干戈板, lit. 'Conflict plank'), Cha Bei (槎碑, can be roughly translated into 'raft stele'), and less formally as Qian Jin Zha (千斤閘, lit. 'Thousand jin floodgate'), this is the Chinese equivalent of portcullis. Unlike European-style portcullis, which is typically constructed as a metal latticed grille, Chinese Cha Ban is built similarly to normal gate door but even more heavily armoured/reinforced, as it is actually expected to function as a floodgate.

Wu Xing Chi (五星池, lit. 'Five star pond')

Wu Xing Chi of the gate of Juyong Pass. Special thanks to The Scholar-General for discovering this and notifying me!

Wu Xing Chi is a special ditch, somewhat similar to a manger/watering trough, that is built directly above the gate doors, with up to five drain holes inside. Its primary purpose is to allow the defenders on the wall to put out fire inside the gateway tunnel (especially if the gate doors catch fire), although the defenders can just as easily pour other harmful liquid down the ditch onto unsuspecting attackers inside the tunnel. One advantage of Wu Xing Chi over regular murder hole is that it allows the defenders to simply pour harmful liquid into the ditch without having to look for a specific murder hole (as handling and pouring dangerous/hot liquid down a regular-sized murder hole can get messy really quickly amidst the chaos of war).

Sloppy illustration of a Wu Xing Chi, from 'Wu Bei Zhi (《武備志》)'. The murder holes actually point downward, not sideways like the illustration.

Despite the importance of murder hole in the defence of a fortification, surprisingly few Chinese city gates are equipped with it. In fact, only a handful of Chinese gates have murder holes at all.

Ordinary murder holes (NOT Wu Xing Chi) of Pan Gate, Suzhou, viewed from above (left), and viewed from inside gateway tunnel (right). To my knowledge, Pan Gate is the only known surviving Chinese city gate with regular murder holes.

Tian Chuang (天窗, lit. 'Sky-window')

Gate of the city wall of Linhai with its exposed Tian Chuang circled red.

Tian Chuang, also known as Tian Jing (not to be confused with the loophole of the same name), is another Chinese counterpart to murder hole. Tian Chuang is much larger than regular murder hole and Wu Xing Chi, and unlike regular murder holes can be found in front of and behind the gate doors, Tian Chuang is always built behind gate doors.

While perfectly functional as a murder hole, it is suggested that the primary purpose of Tian Chuang is actually flood control. During a flood, the gate doors would be sealed shut and Cha Ban lowered. Tian Chuang allows flood workers to fill the empty space between gate doors and Cha Ban with earth (or sandbags in more recent times) to prevent the breaching of gate doors.

Various views of a Tian Chuang.

2.3) Barbicans and outworks

Weng Cheng (甕城, lit. 'Urn fort')

Left: Outer Weng Cheng of the eastern gate of Jingzhou city wall. Right: Triple inner Weng Cheng of the southern gate of Nanjing city wall.

Considered the cream of the crop of Chinese fortification, Weng Cheng is a fortified wall that completely encloses the gatehouse. It is typically rectangular or semicircular in shape, and can enclose the gatehouse from either outside or inside (a few gates have both outer and inner Weng Cheng). The wall of Weng Cheng is usually built to the same height and thickness as the main city wall, and comes complete with its own battlement, gatehouse and tower. Barring a few exceptions (i.e. capital cities like Nanjing and Beijing), the gate of Weng Cheng is always intentionally misaligned from both city gate and drawbridge in order to force enemy troops and siege engines to change direction multiple times before they can reach the main gate.

While usually translated as 'barbican' in English, Weng Cheng actually differs from most forms of castle barbican in design and purpose. A typical barbican is a fortified outpost designed to bolster the defence of a castle entrance and seeks to deter enemy troops from ever reaching the gatehouse. To this end, it is usually built outside the principal fortification limits and only connected to the gatehouse via drawbridge or a raised/walled corridor dubbed "the neck". The neck prevents enemy troops from storming the gate en masse, as moving a large body of troops across such a narrow passage in a short time is all but impossible, although this also prevents the defenders from sortie out to meet their enemies head on.

On the other hand, Weng Cheng is designed to delay enemy assault and, whenever a chance presents itself, lure a portion of enemy troops inside, separate them from the main body of the army, and annihilate them. As such, Weng Cheng is much more spacious than barbican, allowing more troops to get in or out at once. It can also serve as a protected staging ground for the defenders that want to engage their enemies directly.

Nevertheless, in some rare cases a Weng Cheng can also be detached from the main wall and made into a fortlet/proper barbican.

A Ming period map of the Song-era triple cities of Yangzhou, showing the layout of multiple detached Weng Cheng. The city walls have all but disappeared by now, although a few Weng Cheng survive to this day. The circled portion of the map shows the western gate and Weng Cheng of the smaller Jiacheng city (the map is oriented west side up), and the photo at the right shows how they look today.

Yue Cheng (月城, lit. 'Crescent wall')

Yue Cheng can refer to two different types of Chinese fortifications: a permanent fortified bridgehead, and a secondary Weng Cheng.

Permanent fortified bridgehead

A Yue Cheng guarding a crossing of a moat. Image cropped from 'Jing Jiang Fu Cheng Chi Tu (《靜江府城池圖》)', a Song Dynasty city map of Jingjiang (present-day Guilin City) carved onto the cliff of Parrot Mountain.

The first type of Yue Cheng is a fortified gated wall that encloses a portion of a moat or river, which serves as a permanent fortified bridgehead. 

Secondary Weng Cheng 

Yue Cheng of the restored city gate of Zheng Ding.

The second type of Yue Cheng is a fortified gated wall that encloses the gatehouse of a Weng Cheng, essentially functioning as a secondary Weng Cheng itself. Unlike the primary Weng Cheng, the wall of Yue Cheng is thinner and lower than the main city wall, allowing defenders on both walls to engage the enemies at the same time.

Hu Men Qiang (護門牆, lit. 'Door-protecting wall')

Tripled Hu Men Qiang (circled in red) protecting the secondary gates of the Yue Cheng of Song-era triple cities of Yangzhou.

Also known as Dang Men Qiang (擋門牆, lit. 'Door-blocking wall') and less commonly Yong Men (壅門, lit. 'Block door'), Hu Men Qiang is a solitary wall built in front of a city gate without Weng Cheng to hide the gate from enemy observation, as well as protect the gate doors against direct bombardment. Essentially an enlarged and militarised version of spirit screen, Hu Men Qiang is usually built on top of a Que Tai (鵲臺) some distance away from the city gate. During wartime, both sides of Hu Meng Qiang can be barricaded with wooden palisades, enclosing the gatehouse entirely.

There are no known Hu Men Qiang that survive completely intact, although a ruin of Hu Men Qiang, dated to pre-historic Late Yangshao period, has been found at Xishan Site in Henan, showing just how far back such fortifications have existed in China.

A small trivia: Suwon Hwaseong is a Korean fortress built in late 18th century in imitation of Chinese style fortification. The west gatehouse of Hwaseong Fortress has a semicircular chemise wall that partially encloses the gate entrance. While the Koreans called this chemise wall Ongseong (옹성) the equivalent of Chinese Weng Cheng, in Chinese classification it is only considered a Hu Meng Qiang.

2.4) Buildings on the gatehouse

Cheng Lou (城樓, lit. 'City tower')

Front view of the Cheng Lou of Zhengyang Gate, Beijing. 

Cheng Lou or Zhong Men Da Lou (重門大樓, lit. 'Great tower of heavy gate') refers to the great tower sitting on top of the main gatehouse of a city. Unlike other defensive towers on the wall, Cheng Lou primarily serves as a command and observation platform and is built to impress. As such, it typically lacks the fortified brick structure and loopholes of its more defence-oriented counterparts.

Zha Lou (閘樓, lit. 'Floodgate tower')

Zha Lou of the southern gate of Xi'an.

Zha Lou refers to a gate tower that houses the facility to control Cha Ban/portcullis, and sometimes the drawbridge as well. It is typically built on top of the gatehouse of a Weng Cheng or Yue Cheng.

Diao Qiao (釣橋, lit. 'Angling bridge')

Raised drawbridge of the southern gate of Xi'an.

Diao Qiao is the Chinese term for drawbridge. Due to the massive size of Chinese moat, a single wooden drawbridge that spans the entire width of the moat is highly impractical. Instead, drawbridge is typically built at the narrowest point of the moat. Alternatively, a fortified artificial islet can be erected at the midpoint of the moat, with two drawbridges connecting the gatehouse to the islet, and islet to the other side of the moat.

It should be noted that the correct historical term for drawbridge is Diao Qiao (釣橋, lit.'Angling bridge'), which is not to be confused with Diao Qiao (吊橋, lit. 'Hanging bridge') or suspension bridge. However in common/modern usage Diao Qiao (吊橋) can be used to refer to both drawbridge and suspension bridge.

3) Moat

The third part of this series will provide an overview of Chinese moat and its related facilities, as well as their names. As before, italicised names are likely modern terminology.

Hao (壕, lit. 'Moat')

The moat of Xi'an.

Hao is the Chinese term for moat. It is more commonly known as Hu Cheng He (護城河, lit. 'City-protecting river'). As Chinese people built some of the largest and most impressive fortifications in the world, they also dug some of the deepest and widest moats to match their forts. In addition to military purpose, moats also serve an important role in flood control.

A dry moat is known as Gan Hao (干壕) or Huang (隍).

Hu Cheng Chi (護城池, lit. 'City-protecting pond')

Modern line illustration of the layout of Shenbicheng Fortress, with its two defensive ponds highlighted in red.

Hu Cheng Chi is essentially a deep pond dug at a strategic location outside a fortification, in order to deny the ground to enemy siege engines.

3.1) Moat walls

Yang Ma Qiang (羊馬牆, lit. 'Sheep and horse wall')

Drawing of Yang Ma Qiang (highlighted), from 'Wu Bei Zhi (《武備志》)'.

Also known as Niu Ma Qiang (牛馬牆, lit. 'Cow and horse wall') and less commonly Feng Yuan (馮垣), Yang Ma Qiang refers to a small moat wall, or fausse-braye, built on top of a Que Tai (鵲臺) near the bank of a moat (although some moatless cities also have Yang Ma Qiang). Originally designed as a temporary shelter for refugees' livestock in time of war (to avoid congestion of the city gate), before long Yang Ma Qiang was also fortified and installed with an assortment of loopholes and turned into a secondary defensive wall, allowing defenders of two walls to engage the attackers at the same time.

An old photo of the Anding Gate of Beijing. The small wall maked with a red arrow is a Yang Ma Qiang.

Yang Ma Qiang also serves as an obstacle that prevents enemy siege engine from getting too close to the main wall.

Hu Xian Qiang (護險牆, lit. 'Danger-protecting wall')

Comparison between Yang Ma Qiang (left) and Hu Xian Qiang (right). Image cropped from 'Jing Jiang Fu Cheng Fang Tu (《靜江府城防圖》)'.

Like Yang Ma Qiang, Hu Xian Qiang is also a defensive wall built near the bank of a moat. Whereas Yang Ma Qiang is a relatively thin parapet, Hu Xian Qiang is a full-fledged (albeit smaller than the main city wall) fortified wall with its own battlement, towers and gates.