3.1 Timber for forts and other military structures
In the first 150 years A.D. at least seven wooden forts, with sizes between slightly less than one and two hectares, was located in the Rhine delta (Chorus 2007). Little is known about the fort at Bodegraven, but this fort also seems to have covered circa 1 ha (Van der Kooij et al. 2005). Near Katwijk, a stone construction was located that has been interpreted as a fort, and for which the date is unknown (e.g. Bloemers & De Weerd 1984; De Weerd 1986). It is also unknown whether this construction had a wooden predecessor. However, it is likely that a fort was located near the mouth of the estuary in the first century (Bosman & De Weerd 2004; Van Dinter in press). The fort near Vechten was probably larger than the other wooden forts in the delta. This is the oldest fort of the series and was built in the first decades B.C. or A.D. (Polak & Wynia 1991; Zandstra & Polak 2012).
The forts are not the Roman army's only structures. Watchtowers were built and quays were constructed. In the late first century, a road was built, partly with a wooden foundation, which connected the forts (Luksen-IJtsma 2010). Although the building activities did not all take place at the same time, there would have been periods when a large amount of construction wood was required, for instance when the forts and quays were constructed in the 40s A.D., after the Batavian revolt in A.D. 69/70 when many of the forts had burned down, and when roads were built in A.D. 99/100 and 123/125. In between these moments, construction wood would have been needed for renovations and when regiments changed.
The excavations near and in the forts of Alphen aan den Rijn (Haalebos & Franzen 2000; Polak et al. 2004) and Valkenburg (Glasbergen 1972; Glasbergen & Groenman-van Waateringe 1974; Van Rijn in prep.) have provided much information on the use of wood in a military context. Moreover, the Roman road has been investigated in various locations, and wood data have become available for other forts and several watchtowers near the fort of De Meern (Langeveld et al. 2010; Van der Kamp 2007; idem 2009). On the basis of more than 6000 finds of wood, Van Rijn (in prep.) has gained insight into the use of wood in military constructions in the Rhine delta and on the origin of the building material.
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Figure 4a-d Relative amounts of wood taxa used for timber by the Roman army in the western Lower Rhine delta between A.D. 40 and 140, a. in the forts in the early Roman period, b. in the forts in the middle Roman period, c. in the road constructed in A.D. 99/100, and d. in the road constructed in A.D. 123/125. Legend: Abies = A. alba = silver fir; Acer = A. campestre = field maple; Alnus = alder; Fraxinus = F. excelsior = ash; Pinus = pine; Quercus = oak; Ulmus = elm.
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The research on the wood reveals that a wide spectrum of species was used for the construction of the forts and the accompanying quays between A.D. 40 and 70. Alder (Alnus), ash (Fraxinus excelsior) and elm (Ulmus) are the most common species. Oak (Quercus) and field maple (Acer campestre) were used relatively little (fig. 4a). A range of nine species was used for wickerwork, wicker mats and faggots, which adds to the total wood spectrum. The spectrum of used species shows similarities with that of riverine woodland on levees. Because part of the wood that is used in constructions is gnarly and crooked -- which would not be the case when it had been imported -- it is assumed that construction wood from the local woodland on the levees was used for the layout of the military defence system, perhaps complemented with alder wood from the flood basins and fen woodlands.
The period after circa A.D. 70 shows a strong increase in the use of alder, while ash, elm and field maple have almost disappeared (fig. 4b). This leads Van Rijn (2004; idem in prep.) to conclude that the riverine woodland on the levees had become scarce. From the late first century onwards the construction wood of alder was made out of trees which had more or less the same diameters, and consisted of straight stems without side branches. Van Rijn assumes that this alder wood came from coppiced alder woodlands which were managed by man, and which were probably located on the low-lying parts of the levees, in the flood basins and the fen woodlands. This assumption is extremely interesting, since coppiced woodland provides more suitable construction wood per hectare than natural woodland. The assumption that production woodland occurred in the Rhine delta as early as the late first century indicates that the landscape was at that time already adapted to the increased demand for construction wood.
The selection of oak in the period after A.D. 70 seems to have been limited to the construction and maintenance of roads and the river infrastructure, especially in A.D. 99/100 and A.D. 123/125 (fig. 4c-d). Research into the numbers and pattern of year rings has demonstrated that part of the construction wood came from woodland that had been harvested for wood before. Wood with several hundreds of year rings also occurs, and some of it has been investigated dendrochronologically. This has revealed that these oaks have come from natural woodland located in what is now the western part of the Netherlands (Visser 2009; Visser & Jansma 2009).
Apart from the use in building, wood was the main fuel for various activities, such as domestic use (cooking, baking and heating), craft activities and for cremations. Until now, little was known about the use and origin of firewood in military contexts.
The research on wood reveals that the construction wood for the forts and other military constructions, as well as for the wooden foundations of the road, is mainly of local or regional origin. This result fits with the historical research carried out by Kehne (2007, 324). He writes the following:
‘The system of mobilizing material resources to provision the Roman armies in the form of taxes in money and kind was imposed on the new provinces of Gallia, Brittania and Germania. For several reasons the Roman empire never developed an uniform and universally military supply system. The Roman empire had to meet logistic needs of the armed forces on a adhoc basis, with a lot of improvisation but constant improvement of the implemented institutions too.’