Figure 1 . A plan of the castellum Matilo with trench number three marked by the black rectangle , dark blue marks the contour of the fort , and the Corbulo channel is marked by the light blue area ( Courtesy of J . de Bruin ).
Along the Lower Rhine Limes many Roman military objects have been found in rivers ( Nicolay 2007 , 124 ). It has been suggested that these objects were offered by Roman soldiers in rites of passage to Gods in return for their safety ( Nicolay 2007 , 181 ; Roymans 1996 , 32 ). However , no direct evidence for this explanation has been found , indicating that other interpretations of these finds can be just as valid .
Around the first century AD the river Rhine in the Low Countries formed the Limes , the border between the Roman world and everything else . In the Roman period this was known as orbis terrarium and terra incognita ( Hazenberg 2000 , 7 ; Nicolet 1991 in Driessen 2007 , 41 ). Considering the nature of the Dutch Rhine it is possible that liminality was of importance for the potentially ritual depositions along these frontiers .
Three near complete Roman cavalry helmets were found in in the Lower Rhine Limes region . One of these finds , the mask from Matilo near Leiden , was found during the excavation of the Corbulo channel ( which from 50 CE onwards connected the Meuse and Rhine ) ( fig . 1 ) while the other two Roman helmets from Bodegraven and Woerden were dredged up from the Rhine ( Hazenberg 2000 , 36 ; Klumbach 1974 , 54 ; Van Enckevort and Hazenberg 1997 , 38 ; Vos et al . 2010 , 113 ). Because the Matilo mask is thus far the only helmet with a clear archaeological context it provides the unique opportunity to study a possible deposition of a Roman military object found in a wet , possibly liminal and in situ , context .
This article will answer the research question whether the concept of liminality can be applied to the Matilo mask . However , to answer the research question first the sub question whether the Matilo mask was a ritual deposition will need to be answered .