Every new weapon forced fortresses to reinvent themselves
Fortifications have always chased weapons. Tall medieval walls fell to fourteenth-century cannon, so builders went low, sinking walls into ditches behind earth slopes. Nineteenth-century explosive shells shattered those intricate star forts, so steel and concrete took over. After the First World War, large fortresses stopped making sense almost everywhere.
The word comes from Latin fortis, strong, and facere, to make. Some of the oldest fortified sites are surprising. Amnya in western Siberia is described as the northernmost Stone Age fort. Sesklo in Greece had walls by 6800 BC. Near Provadia in Bulgaria, the salt-producing settlement of Solnitsata, begun around 4700 BC, was about 91 metres across and housed some 350 people in two-storey homes inside walls of stone blocks 1.8 metres high and 1.4 metres thick.
Not every wall was purely military. On Orkney, a stone barrier dated to 3200 BC surrounded the temple complex of Ness of Brodgar; this Great Wall of Brodgar, 4 metres thick and as tall, seems to have served a symbolic or ritual purpose. Egyptians guarded the edges of the Nile Valley with frontier fortresses, and much of the ancient world built in mud brick, which is why many fortresses survive only as earthen mounds. Bronze Age Malta produced a bastion at Borg in-Nadur around 1500 BC. Sparta and early Rome stood out by going without walls for a long time, trusting their armies instead.
Greek builders ranged from Mycenae's huge mortarless cyclopean blocks to the Long Walls that tied classical Athens to its port at Piraeus. The phrourion, a small garrison post much like the Roman castellum, watched roads, passes and borders rather than acting as a true stronghold. Since the Roman legions, laying out a camp or fort has been called castrametation, and military engineers distinguish permanent, semipermanent and field works.
Castles form a special category because they were homes of monarchs or nobles controlling a set territory. Descended from Roman forts and hill forts, they emerged in the Carolingian Empire in the ninth century, and some early medieval towns grew up around them. Gunpowder then pushed designs toward low profiles, ditches and earth ramparts that soaked up the impact of cannonballs.
Source: Fortification
