For a vast imperial regime ruling over a galaxy-wide territory while caught in turmoil, what mattered most?
A hundred people might give a hundred different answers, ranging from military and politics to economics and culture, as well as the immense centrifugal forces and separatist tendencies created by excessive spatial distances.
But for the Imperium of Man, which maintained its rule through instruments of violence such as Astartes, there were only two problems that truly troubled it and could not be solved: transportation and communication.
These were also the decisive factors that determined how large an area a regime could effectively govern most of the time.
Communication meant that no matter how far from the center of power a war or rebellion broke out, the central decision-making body could receive the news immediately and respond effectively, ensuring that threats were strangled in the cradle rather than discovered only after they had grown large enough to require armies to suppress them.
The Imperium of Man clearly possessed no mature means of communication across the galaxy. It could only rely on a group of psykers known as "Astropaths" to transmit information through the Warp.
But psykers were notoriously unstable and extremely dangerous, and they were also highly susceptible to Warp Storms, which could completely sever their connection with the center.
Thus, the Imperium's rule over its various star regions had always been loose and fragile. It could only adopt a quasi-feudal system of governors, lords, and nobles to ensure that each region could sustain itself even when cut off from the center, and even possess a certain degree of military strength to resist foreign invasions.
Transportation, meanwhile, meant being able to closely connect every planet throughout that vast territory, whether for trade, cultural exchange, or the large-scale movement of resources and armies.
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