In Britannia the Empire built two walls one behind the other; for Mauretania there was a single wall with forts on both sides of it. In other places, such as Syria and Arabia Petraea, there was no continuous wall; instead there was a net of border settlements and forts occupied by the Roman army. In Dacia, the limes between the Black Sea and the Danube were a mix of the latter and the wall defenses: the was the conjunction of two, and sometimes three, lines of , with a Great Camp and many minor camps spread through the fortifications.