Lecture 20 covers a world upheaval in the 13th and 14th century: Mongol conquests. An important invention that powered the conquests (see map) was a novel use of horses.
Genghis Khan understood the importance of horses and insisted that his troops be solicitous of their steeds. A cavalryman normally had three or four, so that each was, at one time or another, given a respite from bearing the weight of the rider during a lengthy journey. Mongol horses could traverse the most rugged terrain and survive on little fodder.
The horses provided the Mongols with a huge communications advantage. Because horse-mounted troops were so fast it was practically impossible for cities to prepare for an attack. Intelligence, i.e. information about Mongol military movements, could not be delivered faster than the arrival of the Mongol troops to the battlefield. Since standing armies at the time were small, the cities did not have time to gather their forces from neighboring towns and villages. Essentially, the Mongol's "nervous system" worked faster than anything developed by their competitors.
It's the same pattern that worked for telegraph improve the railroad system; radio for tanks and motorized military units; DHL's breakthrough in document delivery; creation and distribution of playlists ahead of music collections; tweets and facebook messages ahead of demonstrations, and etc.
tags: system, payload, communications, control, telegraph, invention