Did medieval kings really lose control over fortress-building after the collapse of the Roman Empire? David Bachrach explores how rulers in the Carolingian and Ottonian worlds maintained authority over major fortifications and the vast labour forces needed to construct them.
By David Bachrach
The right to license fortifications has long been understood as a key element of royal or princely authority and power in medieval Europe. The ability to enforce control over this right has been understood as a sign that a ruler was strong, while the inability to keep control over strongholds or to stop individuals from building new fortifications without the ruler’s permission has been seen as clear evidence of a weak or failed ruler. However, the treatment of this topic with regard to early medieval Europe, a period for which scholars rely largely on material rather than written evidence, has suffered from significant methodological problems. It is possible in this context to identify two scholarly traditions, both of which have led to false narratives regarding the collapse or even absence of royal power in the Carolingian Empire, particularly in the East, and in early medieval Germany.
On the one hand, many scholars have argued that early medieval governments, including the rulers of the Carolingian Empire, sought to control the construction of every type of fortification, ranging in scale from fortified homes to massive, militarily significant fortresses. A key text in this narrative is the Edict of Pîtres, which was issued in 864 by the Carolingian ruler of West France, Charles the Bald (840-877). In this context, the identification of numerous small-scale fortifications, mostly through excavations, has been presented as evidence for the collapse of royal power, particularly from the mid-ninth century onward.
This failure of the power of the king often is explained as resulting from the period of civil wars that engulfed the Carolingian Empire during the latter part of the reign of Emperor Louis the Pious (814-840) and under his sons Lothair (840-855), Louis the German (840-876) and Charles the Bald (840-877). Concomitant with the corrosive effects of these civil wars on royal power, many scholars also emphasize the increasing tempo of attacks by Vikings and Muslims over the course of the later ninth and early tenth centuries.
By contrast with the decline of royal power school, other scholars, particularly those working in the Germanist tradition, have started from the assumption that royal power was never very strong in the post-Roman world. Under this interpretation, “nobles” always operated as the partners or even the competitors of the king and held the inherent right to construct whatever fortifications they wished. Consequently, scholars in this school have interpreted fortifications of all types, including very large-scale fortresses, as the work of “nobles”, operating in their own interest.
In short, scholars have concluded either that royal governments had a broad-based policy against the construction without a license of fortifications of any type, which they could not enforce after the mid-ninth century, or they had no policy or power at all to control the construction of fortifications by “nobles” at any point since the collapse of the Roman Empire.
Rethinking Royal Control over Fortifications
Stuttgart Psalter, early 9th century – Württembergische Landesbibliothek Cod.bibl.fol.23 fol. 146v
Both of these scholarly traditions, however, are based on assumptions that cannot be sustained.
First, early medieval governments, following in the tradition of the later Roman Empire, were not concerned with small-scale fortifications, but rather only with large and militarily significant installations. The former provided defense against low-level threats and/or emphasized the wealth and social prestige of their builders. The latter served strategic functions in territorial defense and as bases of operation for military campaigns.
Recent archaeological work throughout the Gallic provinces of the later Roman Empire has revealed vast numbers of small-scale fortifications, including fortified villas as well as villages, that possessed elaborate systems of protective ditches and wooden fences. Such small-scale fortifications were explicitly permitted by the Theodosian Code. By contrast, later Roman law specifically required government permission for the construction of large-scale fortifications, including the building of walls around an urban center, the addition of towers, and the raising of an internal citadel within the already existing walls of a city.
The vast increase in our knowledge of late antique structures, which has resulted from increasingly effective archaeological techniques, has made clear that the construction of fortified homes of various types as well as the establishment of fortifications around hamlets and villages continued in the period of transition from Roman to Frankish rule. These were not a new phenomenon in the ninth century and were not the result of a collapse of royal authority. Indeed, there is no information in surviving written sources for the effort of any governmental authorities from the later Roman period onward to restrict or license such small-scale fortifications.
The Edict of Pîtres actually has no provisions that address the construction of fortified homes or other types of small-scale installations. Consequently, the identification of large numbers of small-scale fortifications, including those constructed in stone, in the Carolingian Empire of the later ninth century and in the Ottonian kingdom of the tenth and early eleventh century tells us nothing about royal power or authority.
By contrast, royal charters and narrative accounts from the ninth, tenth, and eleventh centuries, including the Edict of Pîtres, do provide considerable information about both the licensing of large-scale fortifications and, just as importantly, the mobilization of labor resources that were necessary to construct them. The Edict of Pîtres states explicitly that: “according to long standing practice which was also exercised among foreign peoples, for work on new fortifications (civitates novae), bridges, and roads through swampy regions, and were also to serve in the garrisons of fortifications and along the frontier.” Large numbers of royal charters as well as narrative accounts make clear that these obligations were enforced throughout the Carolingian Empire and subsequently in early medieval Germany under the Ottonian rulers (919-1024) and under the Salian dynasty at least up through the reign of Henry IV (1056-1106).
University Library of Leiden Cod. Perizoni F.17 fol. 24v
Those scholars who insist that “nobles” in the Carolingian Empire and in early medieval Germany were responsible for the construction of fortifications and, moreover, did so without any need for royal approval, generally do not distinguish between the kinds of fortifications that these “nobles” built. These scholars simply assume that “nobles”, acting on their own initiative, had the material, economic, and administrative wherewithal to construct large-scale fortifications that were militarily significant. They have not assimilated into their models of early medieval society the reality that the scale of resources required to build even exceptionally high-quality residences, with glass windows and heated floors, was orders of magnitude less than that necessitated by the construction of a middling to small mortared-stone fortress. In short, these scholars have failed to ask how or whether such “nobles” could mobilize a sufficiently large labor force, including trained craftsmen of numerous types, to provide anywhere from several hundred thousand to more than a million man-days of labor.
Written sources provide ample evidence that Carolingian, Ottonian, and Salian kings had both the authority and power to mobilize vast labor forces for the construction of large fortresses. Both secular and ecclesiastical office holders, such as counts and bishops, also were able to mobilize these labor resources if they held authority delegated to them by the ruler.
By contrast, there is no evidence from any written source from the ninth or tenth centuries for the authority of any “noble” to mobilize the labor of anyone, including even his own tenants, for work on fortifications in his private interest. The Austrian scholar Michael Mitterauer demonstrated, after an exhaustive survey of the sources, that the earliest evidence for a landlord, in this case the church of Trier, having this authority over its own tenants appears in 1036. It was not until the last decades of the Salian dynasty, during the reign of Henry V (1106-1125), that we can see the first signs of secular aristocrats effectively claiming erstwhile royal powers to mobilize the broader population in pursuit of their private aims.
It is undoubtedly the case that wealthy men and women were able to build fortified homes for themselves in the later Carolingian period as well as under the Ottonian and Salian kings of Germany. Indeed, the growing number of such fortified sites during the course of the ninth century and later, which have been identified by archaeologists, is a testament to the growing wealth of society in this period. However, it is methodologically unsound to argue that because an aristocrat had the economic wherewithal to construct a home surrounded by a stone wall, that wealthy individuals also had the ability to construct militarily significant installations on the basis that the ruler had lost his control over the licensing of fortifications.
Rather, all of the written evidence that we have from the Carolingian, Ottonian, and most of the Salian periods goes in one direction. Only the ruler could authorize the construction of a militarily significant fortress, and only the ruler had the authority to authorize the mobilization of the human and material resources that were necessary for the construction of such a fortification.
David Bachrach is a Professor at the University of New Hampshire, where he researches medieval military history, particularly in England and Germany.
David S. Bachrach, “Feud, Governmental Authority, and the Balance of Power in the Conduct of War in Ottonian Germany,” in War Violence in the Pre-Modern World, ed. Lennart Gilhaus (Leiden, 2025), 27-43.
Top Image: St. Gallen, Stiftsbibliothek, Cod. Sang. 22, p. 141 – Golden Psalter (Psalterium aureum) of St. Gall – Psalterium Gallicanum (https://www.e-codices.ch/en/list/one/csg/0022)
Did medieval kings really lose control over fortress-building after the collapse of the Roman Empire? David Bachrach explores how rulers in the Carolingian and Ottonian worlds maintained authority over major fortifications and the vast labour forces needed to construct them.
By David Bachrach
The right to license fortifications has long been understood as a key element of royal or princely authority and power in medieval Europe. The ability to enforce control over this right has been understood as a sign that a ruler was strong, while the inability to keep control over strongholds or to stop individuals from building new fortifications without the ruler’s permission has been seen as clear evidence of a weak or failed ruler. However, the treatment of this topic with regard to early medieval Europe, a period for which scholars rely largely on material rather than written evidence, has suffered from significant methodological problems. It is possible in this context to identify two scholarly traditions, both of which have led to false narratives regarding the collapse or even absence of royal power in the Carolingian Empire, particularly in the East, and in early medieval Germany.
On the one hand, many scholars have argued that early medieval governments, including the rulers of the Carolingian Empire, sought to control the construction of every type of fortification, ranging in scale from fortified homes to massive, militarily significant fortresses. A key text in this narrative is the Edict of Pîtres, which was issued in 864 by the Carolingian ruler of West France, Charles the Bald (840-877). In this context, the identification of numerous small-scale fortifications, mostly through excavations, has been presented as evidence for the collapse of royal power, particularly from the mid-ninth century onward.
This failure of the power of the king often is explained as resulting from the period of civil wars that engulfed the Carolingian Empire during the latter part of the reign of Emperor Louis the Pious (814-840) and under his sons Lothair (840-855), Louis the German (840-876) and Charles the Bald (840-877). Concomitant with the corrosive effects of these civil wars on royal power, many scholars also emphasize the increasing tempo of attacks by Vikings and Muslims over the course of the later ninth and early tenth centuries.
By contrast with the decline of royal power school, other scholars, particularly those working in the Germanist tradition, have started from the assumption that royal power was never very strong in the post-Roman world. Under this interpretation, “nobles” always operated as the partners or even the competitors of the king and held the inherent right to construct whatever fortifications they wished. Consequently, scholars in this school have interpreted fortifications of all types, including very large-scale fortresses, as the work of “nobles”, operating in their own interest.
In short, scholars have concluded either that royal governments had a broad-based policy against the construction without a license of fortifications of any type, which they could not enforce after the mid-ninth century, or they had no policy or power at all to control the construction of fortifications by “nobles” at any point since the collapse of the Roman Empire.
Rethinking Royal Control over Fortifications
Both of these scholarly traditions, however, are based on assumptions that cannot be sustained.
First, early medieval governments, following in the tradition of the later Roman Empire, were not concerned with small-scale fortifications, but rather only with large and militarily significant installations. The former provided defense against low-level threats and/or emphasized the wealth and social prestige of their builders. The latter served strategic functions in territorial defense and as bases of operation for military campaigns.
Recent archaeological work throughout the Gallic provinces of the later Roman Empire has revealed vast numbers of small-scale fortifications, including fortified villas as well as villages, that possessed elaborate systems of protective ditches and wooden fences. Such small-scale fortifications were explicitly permitted by the Theodosian Code. By contrast, later Roman law specifically required government permission for the construction of large-scale fortifications, including the building of walls around an urban center, the addition of towers, and the raising of an internal citadel within the already existing walls of a city.
The vast increase in our knowledge of late antique structures, which has resulted from increasingly effective archaeological techniques, has made clear that the construction of fortified homes of various types as well as the establishment of fortifications around hamlets and villages continued in the period of transition from Roman to Frankish rule. These were not a new phenomenon in the ninth century and were not the result of a collapse of royal authority. Indeed, there is no information in surviving written sources for the effort of any governmental authorities from the later Roman period onward to restrict or license such small-scale fortifications.
The Edict of Pîtres actually has no provisions that address the construction of fortified homes or other types of small-scale installations. Consequently, the identification of large numbers of small-scale fortifications, including those constructed in stone, in the Carolingian Empire of the later ninth century and in the Ottonian kingdom of the tenth and early eleventh century tells us nothing about royal power or authority.
By contrast, royal charters and narrative accounts from the ninth, tenth, and eleventh centuries, including the Edict of Pîtres, do provide considerable information about both the licensing of large-scale fortifications and, just as importantly, the mobilization of labor resources that were necessary to construct them. The Edict of Pîtres states explicitly that: “according to long standing practice which was also exercised among foreign peoples, for work on new fortifications (civitates novae), bridges, and roads through swampy regions, and were also to serve in the garrisons of fortifications and along the frontier.” Large numbers of royal charters as well as narrative accounts make clear that these obligations were enforced throughout the Carolingian Empire and subsequently in early medieval Germany under the Ottonian rulers (919-1024) and under the Salian dynasty at least up through the reign of Henry IV (1056-1106).
Those scholars who insist that “nobles” in the Carolingian Empire and in early medieval Germany were responsible for the construction of fortifications and, moreover, did so without any need for royal approval, generally do not distinguish between the kinds of fortifications that these “nobles” built. These scholars simply assume that “nobles”, acting on their own initiative, had the material, economic, and administrative wherewithal to construct large-scale fortifications that were militarily significant. They have not assimilated into their models of early medieval society the reality that the scale of resources required to build even exceptionally high-quality residences, with glass windows and heated floors, was orders of magnitude less than that necessitated by the construction of a middling to small mortared-stone fortress. In short, these scholars have failed to ask how or whether such “nobles” could mobilize a sufficiently large labor force, including trained craftsmen of numerous types, to provide anywhere from several hundred thousand to more than a million man-days of labor.
Written sources provide ample evidence that Carolingian, Ottonian, and Salian kings had both the authority and power to mobilize vast labor forces for the construction of large fortresses. Both secular and ecclesiastical office holders, such as counts and bishops, also were able to mobilize these labor resources if they held authority delegated to them by the ruler.
By contrast, there is no evidence from any written source from the ninth or tenth centuries for the authority of any “noble” to mobilize the labor of anyone, including even his own tenants, for work on fortifications in his private interest. The Austrian scholar Michael Mitterauer demonstrated, after an exhaustive survey of the sources, that the earliest evidence for a landlord, in this case the church of Trier, having this authority over its own tenants appears in 1036. It was not until the last decades of the Salian dynasty, during the reign of Henry V (1106-1125), that we can see the first signs of secular aristocrats effectively claiming erstwhile royal powers to mobilize the broader population in pursuit of their private aims.
It is undoubtedly the case that wealthy men and women were able to build fortified homes for themselves in the later Carolingian period as well as under the Ottonian and Salian kings of Germany. Indeed, the growing number of such fortified sites during the course of the ninth century and later, which have been identified by archaeologists, is a testament to the growing wealth of society in this period. However, it is methodologically unsound to argue that because an aristocrat had the economic wherewithal to construct a home surrounded by a stone wall, that wealthy individuals also had the ability to construct militarily significant installations on the basis that the ruler had lost his control over the licensing of fortifications.
Rather, all of the written evidence that we have from the Carolingian, Ottonian, and most of the Salian periods goes in one direction. Only the ruler could authorize the construction of a militarily significant fortress, and only the ruler had the authority to authorize the mobilization of the human and material resources that were necessary for the construction of such a fortification.
David Bachrach is a Professor at the University of New Hampshire, where he researches medieval military history, particularly in England and Germany.
Click here to read more from David Bachrach
Further Readings
Michael Mitterauer, “Herrenburg und Burgstadt,” Zeitschrift für bayerische Landesgeschichte 36.2 (1973): 470–521.
Thomas Kohl, “Befestigungen in der Karolingerzeit und ihr Umfeld: Eine historische Perspektive,” Bronzezeitliche Burgen zwischen Taunus und Karpaten, ed. Svend Hansen and Rüdiger Krause (Bonn, 2018), 191–204.
Simon MacLean, “The Edict of Pîtres, Carolingian Defence against the Vikings, and the Origins of the Medieval Castle,” Transactions of the Royal Historical Society 30 (2020): 29–54.
David S. Bachrach, “Feud, Governmental Authority, and the Balance of Power in the Conduct of War in Ottonian Germany,” in War Violence in the Pre-Modern World, ed. Lennart Gilhaus (Leiden, 2025), 27-43.
Top Image: St. Gallen, Stiftsbibliothek, Cod. Sang. 22, p. 141 – Golden Psalter (Psalterium aureum) of St. Gall – Psalterium Gallicanum (https://www.e-codices.ch/en/list/one/csg/0022)
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