Caesar's bridges over the Rhine absolutely blew my mind. It's an incredible example of military engineering yielding a tremendous advantage. The military handbo

Caesar's bridges over the Rhine absolutely blew my mind. It's an incredible example of military engineering yielding a tremendous advantage. The military handbooks from throughout the full history of the empire also speak maybe less to engineering specifically, but to the advantages of a literate culture in war. The Romans faced many types of opponents over the centuries, many of which they did not have a natural advantage against, in terms of armament. But they did have tremendous amounts of research and strategy, applicable to all sorts of conditions and opponents. And also impressive skills in logistics. When it comes to the a Rhine, it's a mistake to think that the Romans were simply more civilized than the Germanic people. That may have been true at one point in time, but over time, the societies on the borders of the empire gained quite a bit of sophistication. The borders were also porous, and the "barbarians" spent years of their lives in the Roman world. This is a big reason the power vacuum created by the collapse of Roman authority was readily filled by "barbarian" kings. The Anglo-Saxons, Franks, Arabs, and Vikings didn't come out of nowhere. What was lost in the west was institutional complexity. Although it's interesting that the Arabs founded empires that did match Rome in this regard. At least until the Mongols came smashing in. https://en.m.wikipedia.org/wiki/Caesar%27s_Rhine_bridges https://en.m.wikipedia.org/wiki/Caesar%27s_Rhine_bridges