The Shanhaiguan Pass is the gateway from north-east China to the central plains. The three-storey gate tower of the Great Wall is over 30ft (9m) high, and a tablet over the gateway reads ‘First Pass under Heaven’. The sign is a replica of the original, kept inside, which was inscribed in 1472 by Xiao Xian, the most successful scholar in the year’s imperial examination.
The Jiayuguan Pass controls the corridor through Gansu province in the north-west, much of it arid loess (clayey yellow soil) and desert. The fortress, built in 1372 to guard the pass, is made of rammed earth and has walls about 30ft (9m) high, 22ft (6.7m) thick at the base, and just over 6ft (1.8m) wide at the top.
The wall’s height and width varies. In the Badaling section north of Beijing, it is about 26ft (8m) high, 22ft (6.7m) thick at the base, and about 20ft (6m) thick at the top —wide enough for five horsemen or ten marching men abreast. At the Jiaoshanguan Pass in the Yan Shan mountains, from where you can see the sea, the wall is only about 16in (400mm) wide in places.
In the wider parts, battlements about 6ft (1.8m) high line both sides of the wall, and there are towers at roughly 200yds (180m) — two bow-shot — intervals. Some towers are just weather shelters, others have sleeping quarters or storerooms. Beacon platforms for signal fires, some away from the wall, were sited at about 9 mile (15km) intervals, and a signal could be sent across country within 24 hours.
Smoke signals
Beacon signals were sent as smoke during the day or fire at night. According to folklore, smoke signals were often made with wolf dung, because the smoke hung in the sky for a long time.
The number of smoke columns, or fires, lighted at each beacon depended on the message. One column meant the area was being attacked by a small force (under about 500 men). For a large force, such as over 10,000, four separate signals were lit.
Picture Credit : Google
