Along the Lower Rhine, on the northern side of the civitas Cananefatium, lay the northern boundary of the Roman Empire. This boundary consisted of a chain of forts, smaller fortifications, and watchtowers, as well as civilian settlements and military infrastructure. This chain of Roman military structures has been defined by modern scholars using the Latin term limes. Between the 1st to the 3rd centuries, the concept of limes indicated a defined border of the Roman Empire, without referring explicitly to military structures. Only in the 4th century did the term mean a border area that was under the command of an army chief. Although the word limes is sensu stricto not a term from Roman times, it will be employed here within Whittaker's definition: “…a region within which military buildings were constructed both in advance of and behind the line of administered frontiers.” The research area was within a sector of these limes, containing no fewer than seven forts.

On the western side of the research area, along the North Sea and the Helinium, was also a zone of military installations that were part of the coastal defences. These installations were located on the beach ridges and the coastal barrier of Naaldwijk. In addition to the (small) fortifications, civil settlements also developed here. All these settlements were inhabited by the Roman military community. Within these communities were not only Roman soldiers, but also civilians who lived in the vicinity of the encampments. Along the Lower Rhine, this community also included inhabitants of rural settlements, so we are dealing here with a heterogeneous group of people. This chapter first presents a brief review of the creation, functioning, and cessation of the military occupation along the Lower Rhine. It is followed by a discussion of the structures built by the Roman military communities along the Lower Rhine and elsewhere in the area (table 3.1 and fig. 3.1). These data are supported by a wide range of retrieved material remains. Therefore, this chapter concludes with a characterisation of the military communities in the area based on the collected archaeological data.