The limes (LEE-mayz) was the frontier of the Roman Empire. The word first meant a boundary path, and came to mean the border zone with its rivers, roads, forts and, in some places, walls. It was not one continuous fortified line.
Key takeaways
- The frontier ran for more than 10,000 kilometres, and its design varied from place to place [1].
- In some regions it followed rivers, such as the Rhine and Danube, with forts and roads behind them [1].
- Hadrian's Wall in Britannia (annexed AD 43) was begun about AD 122 and complete by the end of Hadrian's reign [2].
- Frontier soldiers were there to deter raiding parties, not to win large wars [1].
How the limes worked
The Latin word limes originally meant a path or balk dividing fields, or a boundary line or marker [1]. The earliest use for a land border is dated to the historian Tacitus in AD 98, and by about AD 122, in the reign of Hadrian, it was being used for the Danube border [1]. After the third century AD it also named a military district under a commander called a dux limitis [1]. Today we use "the limes" for the whole frontier system of the empire.
It was not a single line. The Roman frontier stretched for more than 10,000 kilometres, and it took different forms in different places [1]. Where there was a good river, as on the Rhine, the border followed the water, and forts stood behind it. The Lower Germanic limes was a river border that was not marked by a solid wall, and the Danube border in the province of Noricum was called a ripa, meaning riverbank [1]. In Upper Germany the defences started as a military road, and from about AD 162 to 163 became a barrier of watchtowers, palisades and ditches, about 550 kilometres long in its final form [1]. In northern Britain the border took the form of stone walls.
The soldiers on the limes were not meant to stop a great invasion. Their job was to deter and defeat small and medium-sized raiding parties, and to watch and control who crossed [1]. Large-scale wars were fought by field armies. Borders also moved: they shifted as the empire grew and shrank, and became steadier under Augustus [1].
Parts of the frontier are now a UNESCO World Heritage Site, called Frontiers of the Roman Empire. It was first inscribed in 1987 and has been extended since [1].
An example from our data
Take the northern edge of the empire. Britannia, annexed in AD 43, has an outline of 170,292 km². Within it stood Hadrian's Wall. English Heritage records that work on the Wall began in AD 122 and that by the end of Hadrian's reign in AD 138 the great Wall was complete, supported by milecastles, towers and forts, with a total garrison of nearly 10,000 men [2]. The Antonine Wall in Scotland was used for a short time further north [1]. Our data stops at the Britannia outline: the map does not draw either wall.
On the Rhine, look at Germania Inferior, annexed in 51 BC, whose capital was Colonia Claudia Ara Agrippinensium. The river was the border here, rather than a wall [1]. On the Danube side, Dacia is a reminder that a frontier could move: it was annexed in AD 106 and lost in AD 271, so the frontier jumped across the river and back again.
Set the date to AD 117 and switch on Provinces and Roads to see the edge. Roads on the map are the network of about AD 150, whatever the date. The homepage borders section explains why this edge is only an estimate, and the how big section covers the empire's size.
The thing people get wrong
Many people imagine the limes as a Great Wall of China around the whole empire. It was a mix of rivers, roads, watchtowers, forts and, in a few places, walls, with different designs from place to place [1]. It was also not an impenetrable line. A river or wall marked where the army stood, not a barrier that nobody crossed, and trade and people moved across it all the time.
Another mistake is to treat the limes as the exact border of the empire. Some peoples lived beyond it but traded with Rome, and some kingdoms close to it were allies. The entry on client kingdoms explains why that makes the edge hard to draw.
Frequently asked questions
Was the limes a wall?
Only in some places. Along the Rhine it was a river border defended by camps, not a wall. Hadrian's Wall in Britain and the Antonine Wall further north are the best known solid barriers.
How do you say limes?
Roughly LEE-mayz. The plural is limites.
Does the map show the limes?
No. The map has no layer for walls, forts or frontier lines. It shows province outlines and the edge of the empire at each date.
Sources
- Limes (Roman Empire), Wikipedia.
- History of Hadrian's Wall, English Heritage.
- Every figure from our own map is worked out from the datasets on the data sources page (checked against Ancient World Mapping Center outlines and Pleiades).