Ian Mortimer is the author of this excellent book, here was one of my favorite bits:
It may seem preposterous today to describe a 5 mph increase in the maximum land speed as revolutionary. It sounds like someone pointing to a hillock and calling it a mountain. But it was revolutionary, for a number of reasons. Like a one-degree rise in average global temperature, it represents a huge change. This is because it is not a one-off event but a permanent doubling of the maximum potential speed. By 1600 the fastest riders could cover 150 miles in a day and individual letters carried by teams of riders could travel at speeds of up to 200 miles per day. This significantly reduced the time it took to inform the government about the goings-on in the realm. If the Scots attacked Berwick when the king was at Winchester, and the news came south at 40 miles per day, as it is likely to have done in the eleventh century, it would have taken nine days to arrive. After the king had deliberated what to do, if only for a day, the response would have travelled back at the same speed — so the north of the kingdom would have been without royal instructions for almost three weeks. If, however, the post could carry the news at 200 miles per day, the king and his advisers could decide on a response in less than two days. After a day’s discussion, the king’s instructions would have been back in the Berwick area less than five days after the danger had arisen — two weeks faster than in the eleventh century.
It is hard to exaggerate the political and social implications of such a change. The rapid delivery of information allowed a king far greater control over his realm…The rise in travelling speeds subtle shifted the balance of power away from territorial lords and towards central government.
The speed of information thus created a demand for more information.
That meant, among other things, more spies. And there was this:
Looked at simply as a statistic, an increase in speed of 5 mph is not very impressive. In terms of the cultural horizons explored in this book, however, it is profoundly important. Imagine the rings spreading out from where you are now — the first ring marking the limit of how far you can travel in one day, with a further ring beyond it marketing two days, and then a yet further ring marking three days. Now imagine all those moving further and further outwards, each one twice as far…you haven’t just doubled or trebled the area you could cover in one, two or three days, you’ve increased it exponentially…With the collective horizon also increasing exponentially, you can see how a doubling of the distances people could travel in a day had a huge impact on the nation’s understanding of itself and what was going on within and beyond its borders.
Interesting throughout, this one will make the year’s “best of non-fiction” list. You can buy it here.