How was the Great Wall of China defended?

In order to defend the enemies successfully, some construction units were built to form the complete and solid Great Wall of China defense system in addition to the walls, like passes to station troops and beacon towers to deliver messages when enemies approached. 

Along the Great Wall of China there are many passes, where soldiers or troops used to station, like Juyongguan Pass, Shanhaiguan Pass and Jiayuguan Pass. When there was a battle, they could move via the wall to the battle site in no time. To strengthen the defensive ability of the passes, defensive towns and other military units with soldiers were set nearby.

For instance, in the Ming Dynasty (1368 – 1644 AD), there were eleven defensive towns with troops set along the Great Wall. These towns were all built with thick bricks and stones surrounded by quite high walls, which were easy to hold but hard to attack. Here is a list of troops’ distribution conditions in the Ming Dynasty.

Defensive Units	Number of Soldiers
Town	3,000 soldiers or according to the actual military conditions
Road Town	More than 12,000 soldiers
Wei Suo	5,600 soldiers
Qian Hu Suo	1,120 soldiers
Bai Hu Suo	112 soldiers
Zong Qi	More than 50 soldiers
Fen Qi	About a dozen

Juyongguan Pass, Beijing

A Beacon Tower at Jinshanling Section

As early as in the Zhou Dynasty (1046 – 256 BC), the method of using beacon towers to deliver message were already in operation. As a primary communication media, beacon towers made a great contribution to the ancient military battles.
 

The beacons towers were built a certain distance along the defense line, and firewood was put in the towers. These towers were usually built on relatively high sites, which were easy for the soldiers to observe the enemies’ situation. When the soldiers found the enemies moving closer, they would burn the firewood piece by piece to send military signals with fire or smoke, which could warn the troops. They usually used smoke in the day time and fire at night.

Beacon Tower Signal Rules in the Ming Dynasty:

Day	Night	Number of Enemies
One smoke torch, one cannon signal	Fire torch, one cannon signal	About 100
Two smoke torch, two cannon signal	Fire torch, two cannon signal	About 500
Three smoke torch, three cannon signal	Fire torch, three cannon signal	About 1,000
Four smoke torch, four cannon signal	Fire torch, four cannon signal	About 5,000
Five smoke torch, five cannon signal	Fire torch, five cannon signal	About 10,000

Apart from the beacon tower signal system, there is another important post system on land along the Great Wall, which consists of post towns, delivery stations and post houses, providing accommodation and horses for the officers who deliver the messages, as well as the safe guard for the military supplies. 
 It is roughly estimated that there are more than 10,000 watchtowers along the Great Wall of China. The exact number is hard to figure out, since the walls were built in different periods and some sections were already destroyed.

 

Due to the huge length of the Great Wall of China, it is impossible to set soldiers along the every inch of it. So the soldiers usually patrolled on the top of the wall to guard the Great Wall of China. The passages on the top of the wall were usually constructed widely. During the battles, the broad passages also make a great contribution on troop’s movement and supplies’ delivery at the highest speed; also, the wall itself is a protection for soldiers from direct attack by enemies.

Further Reading:

 Military Defense System of China Great Wall

 Who was the Great Wall of China built to keep out?

Did the Great Wall of China Work?