History of castle building in East Frisia

from Wikipedia, the free encyclopedia
The lost Greetsiel Castle

The history of castle building in East Friesland shows the architectural and historical development of castle building in East Friesland from the beginnings made of wood to large defensive buildings made of brick. It includes the area of ​​the districts of Aurich , Leer and Wittmund as well as the independent city of Emden .

Rulership and defense construction took a fundamentally different development in East Frisia than elsewhere in Central Europe. Thus, a comprehensive system of rule could not be established, nor did the East Frisians accept the representational attributes of knighthood and nobility before the 15th century . In contrast, the East Frisian social structure provided for property as property. As an independent architectural style, the stone house has emerged as an East Frisian variant of the Donjon , of which only a few have survived in the region. Most of the castles were destroyed after the transition from East Frisia to Prussia (1744), others were converted into palaces. Characteristic for East Friesland are castles made of brick, which were built on terps .

historical development

It is not known when castle construction began in East Frisia. Prehistoric and early historical defenses have not yet been discovered in the region. Possibly they were unnecessary as the land was protected in the north by the North Sea and in the south by vast swamps. The division of the landscape by marshland and moor also ensured that the settlement areas were divided into small parts, which did not allow for a comprehensive rulership.

After the region was incorporated into the Franconian Empire, East Frisia became the target of multiple Norman incursions from the 9th century onwards , in which the population was left to fend for themselves. Charlemagne organized the defense of the country by setting up a coast guard in Friesland along the coast and especially at the estuaries, which relied on the self-help of the armed and loyal Frisians . So far it is unknown where the inhabitants of the area sought protection against the invaders and whether defenses were built for them. In fact, with the victory in the Battle of Norditi in 884, the Vikings were permanently expelled from East Frisia, but they were a constant threat. The East Frisian men were released from military service in foreign territories. From this the Frisians developed the political myth that Charlemagne was the founder of the Frisian freedom , but this was probably only granted later. For this purpose, the cooperatively organized dike construction began around the year 1000 , which connected the East Frisian regional communities between 1150 and 1250 in a loose union.

Seal of the Upstalsboom Association (1324) with an idealized representation of Frisian warriors

As a result, no aristocratic structures could prevail in Friesland for centuries, while the feudal lords ruled in Europe . Towards the end of the Carolingian era , a network of districts that were increasingly disconnected from the ruling groups in the heartland of the Franconian Empire, the state communities, which symbolically referred to themselves as the Seven Seas . In this anti-feudal mood, the armed knight , the sareda riddere, became the enemy par excellence, to whom the Frisians opposed their self-image in a foot warrior armed with a lance or sword and round shield . Accordingly, they hated the castle as an expression of feudalism and the building of one was forbidden to individuals. The first castles were probably built on the outskirts of the state communities and were built by them to defend against their neighbors. Examples of this are the Schlüsselburg near Detern and the Borgholt Castle near Ardorf .

The large number of Frisians with their own farm, the so-called “Eigenerfden” or “Eigenbeerbten”, were, according to their own claim, equal in respect and personality during the period of the so-called Frisian freedom , although there was an upper class of large landowners (“potentes “) Who held the real power in their hands. The Consules or Redjeven , who presided over the regional parishes , mostly came from their circle .

From the 13th century onwards, Frisian freedom fell into disrepair . The development was very different in the individual regional communities. While some became dependent on local families at an early age, others still retained their Republican constitution. The provincial communities tried to prevent the first attempts at local rulership training and the associated building of castles with a ban. For example, it says in the Brokmer Letter , a legal source from the 14th century:

"The brokmen make this a law that there may be no castles, no walls and no tall stone houses with (a fine of) eight marks ... Any stone house is built higher than twelve rod feet high in the square, and a cellar over two house fans in the square enough, the one to whom it belongs pay eight marks. "

- Brokmer Law, § 150
Tower of the Bunderhee stone house

Especially in the marshland areas, the meeting of trade and agriculture in places with direct access to the sea ensured that individual families accumulated so much power that they were able to defy the ban on building castles and stone houses as early as the 13th century. The owners of the oldest stone houses were socially better off people (so-called nobiles ), but initially they did not hold any leadership role in their respective regional communities. These families, whose wealth was based on rural economies, did not live in their castles, but were financially able to build and maintain them. Their stone houses were therefore not isolated, but formed the representative part of an estate characterized by agriculture and / or trade. Over time, it became common for wealthy families to own a stone house, so there could even be several of them in one place. For example, up to five of these buildings could have stood in Stapelmoor . Little by little the buildings developed into pure residential towers.

In the further course of the 14th century, events such as the outbreak of the plague and major storm surge catastrophes further destabilized the situation. The families who owned were able to cope with the damage more easily than poorer families and thus became more and more powerful. Finally they created a system of rule in which they, as “ chiefs ” (hovedlinge), seized power over more or less large areas. In the course of the 14th century feuds developed among the individual chief families, which led to armed conflicts. To finance these disputes, the hijacking of ships served as well as the deliberate stranding of merchants by means of false beacons . Until the end of the 14th century, the power struggles of the chief families were a local problem. After the Vitalienbrüder had been expelled from the Baltic Sea island of Gotland by the Teutonic Order in 1398 , they were accepted by some of the East Frisian rulers who used them as a force. The pirates benefited from the seclusion of East Frisia on land routes with simultaneous access to many chiefs' seats on the sea routes off the East Frisian coast. This created considerable tensions with the Hanseatic League . The cities of Hamburg and Bremen in particular saw themselves damaged by the pirates. In the period that followed, their armies invaded East Frisia several times and destroyed several stone houses. To protect their own interests, the Hamburgers built castles in Stickhausen and Leerort from 1435 onwards .

It was not until the rise of the Cirksena around 1430, when Edzard Cirksena had asserted himself as the leader of a League of Freedom , that this phase marked by long feuds ended, but at the same time the special status of the regional social constitution. Ulrich Cirksena , a member of one of the last influential chief families, was in 1464 by Emperor Friedrich III. raised to the status of imperial count and enfeoffed with East Friesland as imperial county. It belonged to the Lower Rhine-Westphalian Empire . The Hamburgers then withdrew their garrisons in 1453 and handed over their castles to the East Frisian Count House .

The preserved outer bailey in Pewsum

With the establishment of sovereignty of the Cirksena, most of the chief castles lost their defensive function. Many were converted into representative four-wing complexes with a large inner courtyard, such as Hinta Castle . Other chieftain's castles bear witness to the economic decline of their owners, who were absorbed into the group of richer farmers. Mention should be made of the Osterburg in Groothusen , which developed into a large farm estate.

The Cirksena also had many of the castles in their possession remodeled for different purposes. So let Ulrich I. castles in Emden and Aurich to residences and headquarters, the castle Greetsiel expand to a four-winged building with tower. Berum Castle was built during the reign of Count I. Ulrich to a castle with three-blade main and outer bailey . In Pewsum, the Cirksena had a large moated castle built next to the Manningaburg there, while the actual castle was converted into a stone house in the style of the Dutch Renaissance. From then on, the complex served as a summer residence and a widow's residence. Above all, the castles on the borders of the county continued to serve for defense and were greatly expanded, such as Friedeburg , Leerort and Stickhausen. The facility in Leerort thus became the strongest fortress in East Frisia. These castles have been the target of attacks several times. For example, during the Saxon feud, Heinrich von Braunschweig-Wolfenbüttel entered East Friesland with an army of 20,000 men in 1514 and besieged the Leerort fortress, which was only defended by a few farmers and soldiers. During the siege and shortly before a storm attack, one of those trapped managed to kill the duke on June 23, 1514 with a targeted cannon shot. The troops, which had become leaderless as a result, then failed to storm the fortress and withdrew from East Frisia.

In the course of the conflict between the East Frisian estates and the Counts of East Frisia, the Netherlands, as the protective power of the estates, quartered a garrison in Leerort in 1611. In Osterhusischen chord this occupation was subsequently legitimized on May 21 of that year and determined. The first Dutch captain was given the job of repairing the somewhat dilapidated facility immediately. Despite repeated requests to leave the fortress, the Dutch stayed in Leerort until 1744. In that year, East Friesland fell to Prussia after the local dynasty of counts and princes had died out. For the new ruler, Frederick II , the defenses and the castles were no longer of any importance. The fortresses Leerort from 1749 and Friedeburg were demolished in 1763 and most of the castles were demolished.

construction materials

East Frisia is poor in natural stone deposits. Up until the High Middle Ages there were only wood and wood and clay buildings in the Frisian coastal area. The few boulders that existed in the region were transported to East Frisia by glaciers during the Ice Ages and were only used to build churches. Even moderate Rhenish tuff has been used only for sacred buildings. The first castles consisted exclusively of raised sand walls in which there were structures made of wood. It is unclear to date whether a half-timbered construction was built due to the few surviving legacies. Massive structures could only be erected when brick became established as a new building material from the 13th century , after the East Frisians learned the art of making weather-resistant bricks from the abundant clayey earth from monastic orders . In this way, with the help of wandering brick masters, the blanks, which were cut into wooden molds, could be burned into red bricks in large piles . This happened in connection with the social and economic rise of individual families in the coastal towns at the end of the 13th century. All of the preserved buildings of castles in East Friesland are brick buildings that were erected from the 13th century in the fertile marshland where the clay-containing building material was abundantly available and the population was protected from flooding since the dyke was built.

Castles according to the time they were built

Regional castles

So far only two regional castles are known.

The Schlüsselburg was built on the border between the Moormerland and the Ammerland. When exactly their construction began is unknown. A precise archaeological investigation has not yet taken place. Parts were uncovered during a rescue excavation in 2002. The archaeologists found that the castle had unusually wide moats. These were around 15 meters wide on the west side and almost 19 meters wide on the south side and trough-shaped in cross-section. In addition, the remains of a bridge came to light during this excavation.

A second regional castle stood in the area of ​​today's village of Borgholt near Ardorf . In the Middle Ages, this was in the border area between Harlingerland and Östringen . The complex, which is now overgrown by wood, consisted of two roughly equal parts, of which the eastern area, the so-called outer bailey, measures around 22 × 32 meters, while the western area is around 19 meters wide and around 24 to 29 meters long . Both parts with an almost rectangular floor plan are separated by a ditch and protected from the outside by another surrounding ditch. The plant was built between the 10th and the 11th / 12th. Century cultivated.

Stone houses

Typical stone house of the East Frisian chiefs, the Harderwykenburg in Leer

Stone houses are the East Frisian variant of the Donjon . As an independent design, they emerged around the middle of the 13th century in the territories of the Frisian chiefs between the IJsselmeer and the Lower Weser. In their basic form, the buildings measure from eight by twelve to twelve by 15 meters. They usually stand on rectangular sandstone foundations about three meters wide and up to 1.5 meters deep. Most of them were built on the ground. The lowest floor served as a cellar, above which one or two more floors were usually raised. As a defense, the facilities were mostly surrounded by a moat, with the excavation of which the initially free-standing cellar was filled in. Bricks in the form of a monastery were used in the construction of the oldest stone houses . The entrance, accessible via a wooden staircase, was on the first floor. In this there was also the access to the cellar, in which there was a well for the water supply. A free-standing gable and a saddle roof set back inward are also typical of stone houses.

The development of the stone houses at the Beningaburg, which has been partially archaeologically examined, can be demonstrated as an example . There, in the late High Middle Ages, a terp was raised over the bank of a navigable creek of the now largely silted up Leybucht , on which a rural property was built. From the few found artefacts from the oldest settlement horizon, layers with mussel horror from the 9th century, no outstanding social position of the residents could yet be proven. For the late 12th and early 13th centuries, two wooden construction phases have been identified, which were dendrochronologically dated to the period "after 1175" and "after 1238". Due to the small excavation area, it is not yet possible to say whether the recovered wood is the remains of a purely rural building or a defensive structure such as a defense tower. The terp was probably extended by more than a meter in the first half of the 14th century. Then a stone house was built as a representative building for a chief family.

The early stone houses were built as a single-storey brick building over a rectangular floor plan with a gable roof. Later buildings have two to three storeys on a narrow, rectangular, one-room floor plan with pitched roofs and steep gables. The cellars were mostly vaulted and provided with a well. The undivided rooms on the upper floors were equipped with chimneys, the smoke of which was drawn off via a chimney in the gable.

With ramparts and moats, the buildings have all the characteristics of a castle. The stone houses were at the same time a fortress and residence of a small potentate, usually with a limited sphere of influence. In addition to their military use, the (expansion) construction of castles is evidence of a growing sense of class: The chiefs moved closer to the nobility and thus once again widened the gap between the common peasants, who from this time as undersate , as subjects, was considered.

Of the stone houses that were once numerous, very few have survived today, such as the Bunderhee stone house . In the 15th and 16th centuries, their owners had most of them made more homely by installing larger windows and chimneys, which increasingly lost their defensive character.

Hamburg castles

Leerort fortress in 1632

To protect their interests, the Hamburgers had two fortresses built in strategically favorable locations in East Frisia in 1435. This is how the Leerort fortress was built on a promontory between the Ems and Leda. For the construction of this facility, which lasted two months, parts of the destroyed were Focke Castle Focko Ukena used from Leer. Stickhausen Castle was built at the end of a sand ridge at an important junction on the Jümme . Stones from a fortification destroyed by the Hamburgers, the Schlüsselburg near Detern, were also reused for its construction. Both were earth fortifications with a stone building in the center. Later the castle in Stickhausen was expanded by the Hamburgers to include an outer bailey, farm buildings, ramparts and additional moats.

From the stone house to the hall building to multi-wing systems

Hall construction of the Osterburg in Groothusen.

With the establishment of the Cirksena rule, the importance of the castles as defensive structures decreased. In contrast, the need of the aristocratic East Frisian upper class to erect representative buildings increased. Many stone houses were then replaced by one, mostly two-storey, narrow but long hall buildings. The beginning marks the Osterburg in Groothusen, which was rebuilt after its destruction around 1490. In place of the old stone house, a two-storey building was built. With the hall buildings, which had a representative rather than defensive character, the development towards multi-wing water castles and palaces was initiated in recent times.

In the 15th and 16th centuries, side wings were added to the buildings. The expansion of the aristocratic-owned hall buildings may be related to the takeover of the hall by non-aristocratic members of the local upper class. The type varies depending on the position of the owner. The poor aristocrats expanded their houses into three-wing complexes by adding a Gulf barn (for example near the Osterburg in Groothusen) and a wing with living and utility rooms to the hall buildings for agricultural purposes. The most influential families, on the other hand, built castle-like four-wing complexes with a small inner courtyard (examples are Hinta Castle and the Norderburg in Dornum ). Almost all of these buildings are surrounded by grafts.

Jumps

Dieler ski jumps. The Jemgumer Zwinger (2019)

The so-called entrenchments are a special form within the East Frisian defenses . They were built in the late Middle Ages and early modern times at strategically favorable locations, mostly on watercourses in combination with inaccessible moorland areas. Especially at the time of the Dutch War of Liberation from 1568 to 1648, numerous of these systems were built in the German-Dutch border area to protect cities and trade routes.

This is how the main facility of the Dieler Schanze was built in the 14th century on a ridge between a bend in the river Ems on one side and extensive moorland areas on the other. In the immediate vicinity of the ski jump, in the Middle Ages, a trade route led from the Münsterland to East Frisia over the high, dry Geestrücke near Diele, which may be of older origin. Up until the early modern era, this route was the only way to get from the Emsland to East Frisia. To the west, further ramparts and ditches as well as smaller jumps about two kilometers wide secured the old traffic route and further to the west the moor joined as a natural obstacle. The main hill was secured by a double earth wall and a ditch and was accessible via a drawbridge on the northwest side. Four walls surrounded the hill, at the corners of which four towers were built. Inside stood the commandant's house and the barracks for the soldiers. The facility was occupied several times by foreign troops. In 1637 Hessian troops, which occupied East Friesland during the Thirty Years' War , were quartered in the Dieler Schanze. Ten years later, imperial troops conquered the hill and expanded it by tearing down houses in the village and strengthening the hill with the building material obtained in this way. A total of up to 400 soldiers are said to have been stationed in the fortress. In the 17th century, however, the hill was temporarily only manned by 7 men. Much of the facility has been destroyed today. Only the main hill with a double rampart and ditch, which is probably the most recent expansion phase from the Thirty Years' War, is still clearly visible.

The Heseler Schanze was probably built before the Thirty Years' War. Together with the Rhaude, Detern and Potshausen ski jumps, it probably belonged to the Stickhausen Fortress system. They were then probably used during the Thirty Years' War. Today it is also largely destroyed. A pentagonal wall about one meter high remained, of which the southern part is missing. Inside the wall there is also a pentagonal trench and a well. The remains of the ramparts that have been preserved are around 200 meters wide, those of the moat are around 120 meters wide.

A specialty is the border fortress Neuschanz (Nieuweschans). Ernst Casimir von Nassau-Dietz , governor of Friesland , Groningen and Drenthe , left this (then called Langackerschanze ) on the new road Groningen - Bremen occupied two years earlier Create East Frisian soil. Created with practically no legal basis, the East Frisians only received compensatory payments many years later. It was of strategic importance in the Eighty Years War and survived several attacks in the centuries that followed, but was razed around 1815 . To this day the place protrudes into the East Frisian area.

literature

  • Sonja König, Vincent T. van Vilsteren, Evert Kramer: From chiefs and castles. In: Jan F. Kegler, Ostfriesische Landschaft (Hrsg.): Land der Entdeckungen (= land van ontdekkingen. ) The archeology of the Frisian coastal area. Ostfriesische Landschaftliche Verlags- und Vertriebsgesellschaft, Aurich 2013, ISBN 978-3-940601-16-2 , pp. 283-295.
  • Andreas Hülser, Reinder Reiners: Of city walls, stone houses and entrenchments - fortifications and fortifications in the north of the Netherlands and in East Frisia. In: Jan F. Kegler, Ostfriesische Landschaft (Hrsg.): Land der Entdeckungen (= land van ontdekkingen. ) The archeology of the Frisian coastal area. Ostfriesische Landschaftliche Verlags- und Vertriebsgesellschaft, Aurich 2013, ISBN 978-3-940601-16-2 , pp. 313–321.
  • Rolf Bärenfänger : East Frisian Defense. Stone houses and castles. In: Matthias Utermann (Hrsg.): Archeology of medieval castles (= communications of the German Society for Archeology of the Middle Ages and Modern Times. No. 20). German Society for Archeology of the Middle Ages and Modern Times V., Paderborn 2008, ISSN  1619-1439 , pp. 69-76 ( dgamn.de PDF; 3.55 MB).
  • Hajo van Lengen : Castle building and urban development. In: Rolf Bärenfänger: Guide to archaeological monuments in Germany. Volume 35: Ostfriesland , Stuttgart 1999, ISBN 3-8062-1415-8 , pp. 128-140.
  • Günter Müller: 293 castles and palaces in the Oldenburg - East Frisia area. Oldenburg 1977.
  • Kurt Asche: The Frisian stone house. In: Insights. Research magazine of the Carl von Ossietzky University of Oldenburg. Issue 25 of April 1997, accessed June 14, 2012.

Individual evidence

  1. ↑ a b c d e f g Sonja König, Vincent T. van Vilsteren, Evert Kramer: From chiefs and castles. In: Jan F. Kegler, Ostfriesische Landschaft (Hrsg.): Land der Entdeckungen (= land van ontdekkingen. ) The archeology of the Frisian coastal area. Ostfriesische Landschaftliche Verlags- und Vertriebsgesellschaft, Aurich 2013, ISBN 978-3-940601-16-2 , pp. 283-295.
  2. ↑ a b c Andreas Hülser, Reinder Reiners: Of city walls, stone houses and entrenchments - fortifications and fortifications in the north of the Netherlands and in East Friesland. In: Jan F. Kegler, Ostfriesische Landschaft (Hrsg.): Land der Entdeckungen (= land van ontdekkingen. ) The archeology of the Frisian coastal area. Ostfriesische Landschaftliche Verlags- und Vertriebsgesellschaft, Aurich 2013, ISBN 978-3-940601-16-2 , pp. 313–321.
  3. ^ Rolf Bärenfänger : Ostfriesische Defense. Stone houses and castles. In: Matthias Utermann (Hrsg.): Archeology of medieval castles (= communications of the German Society for Archeology of the Middle Ages and Modern Times. No. 20). German Society for Archeology of the Middle Ages and Modern Times V., Paderborn 2008, ISSN  1619-1439 (Print), ISSN  1619-148X (Internet), pp. 69–76 ( dgamn.de ( Memento of the original from November 25, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this note. PDF; 3.55 MB). @1@ 2Template: Webachiv / IABot / www.dgamn.de
  4. ^ Hajo van Lengen : Castle building and urban development. In: Rolf Bärenfänger: Guide to archaeological monuments in Germany, Vol. 35 East Frisia. Stuttgart 1999, ISBN 3-8062-1415-8 , p. 132.
  5. ↑ Hajo van Lengen: Peasant freedom and chief glory in the Middle Ages. In: Karl-Ernst Behre , Hajo van Lengen (Ed.): Ostfriesland. History and shape of a cultural landscape. Ostfriesische Landschaftliche Verlags- und Vertriebsgesellschaft, Aurich 1995, ISBN 3-925365-85-0 , p. 115.
  6. ^ Wolfgang Rüther: House building between national and economic history. The Krummhörn farmhouses from the 16th to the 20th century. Diss. Münster 1999, p. 36 ( repositorium.uni-muenster.de PDF; 1.8 MB).
  7. ^ Wolfgang Rüther: House building between national and economic history. The Krummhörn farmhouses from the 16th to the 20th century. Diss. Münster 1999, p. 37 ( repositorium.uni-muenster.de PDF; 1.8 MB).
  8. ↑ a b Wolfgang Rüther: House building between national and economic history. The Krummhörn farmhouses from the 16th to the 20th century. Diss. Münster 1999, p. 27 ( repositorium.uni-muenster.de PDF; 1.8 MB).
  9. ↑ See Wybren J. Buma, Wilhelm Ebel (Ed.): The Brokmer Law. Vandenhoeck & Ruprecht, Göttingen 1965, ISBN 3-525-18151-5 , p. 91 ( books.google.com ), viewed April 16, 2011.
  10. ^ Hajo van Lengen, Erik Peters, Wolfgang Schwarz: The castle of Beninga in Werdenum in East Frisia. Oldenburg 2003, ISBN 3-89598-921-5 , p. 29.
  11. ↑ Thomas Hill: The city and its market: Bremen's surrounding and external relations in the Middle Ages (12th – 15th centuries). Steiner, Stuttgart 2004, ISBN 3-515-08068-6 , p. 292.
  12. ^ Heinrich Schmidt: Political history of East Frisia. Self-published, Leer 1975, p. 79.
  13. ↑ Niedersachsen.de: History of the Regions: Ostfriesland ( Memento of the original from February 1, 2009 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.niedersachsen.de
  14. ^ Karl-Klaus Weber: Resolutions of the States General 1576–1625: Dutch Regests for the history of East Friesland and the city of Emden. Norderstedt 2007, ISBN 978-3-8334-8789-7 , p. 341.
  15. ↑ a b Wolfgang Rüther: House building between national and economic history. The Krummhörn farmhouses from the 16th to the 20th century. Diss. Münster 1999, p. 85 ( repositorium.uni-muenster.de PDF; 1.8 MB).
  16. ^ Hermann Haiduck: The architecture of the medieval churches in the East Frisian coastal area. Verlag Ostfriesische Landschaft, Aurich 1986, ISBN 3-925365-07-9 , p. 13.
  17. ↑ Robert Noah: God's houses in East Friesland. Soltau-Kurier, Norden 1989, ISBN 3-922365-80-9 , p. 48.
  18. ↑ a b Rolf Bärenfänger, archaeological service of the East Frisian landscape : Detern (2002) , viewed on June 13, 2012.
  19. ↑ Hajo van Lengen : Report on the first test excavation in 1972 on the Borgholt castle complex, Ardorf municipality, Wittmund district , in: Ostfriesische Fundchronik 1971/1972. Accessed June 13, 2012.
  20. ↑ Kurt Asche: The Frisian stone house in: Insights. Research magazine of the Carl von Ossietzky University of Oldenburg. Issue 25 of April 1997, accessed June 14, 2012.
  21. ^ Heinrich Schmidt: The eastern Friesland around 1400. Territorial-political structures and movements , in: Wilfried Ehbrecht (Ed.): Störtebeker - 600 years after his death. Trier 2005, p. 89.
  22. ↑ town of Leer: Chronicle data Leeraner Stadtgeschichte- Chronicle data: 1000-1699 , reviewed on January 26 of 2010.
  23. ↑ Hartmut Georg Urban: Comments on fortifications of the 15th century in East Friesland Part 2: Castles with a hall house . In: Castles and Palaces. Vol .: 49, No. 1, 2008. pp. 14-28 ISSN  0007-6201 .
  24. ↑ a b c Paul Weßels (local chronicle of the East Frisian landscape): Diele, city of Weener, district of Leer (PDF; 429 kB).
  25. ↑ AH van Slageren: Fortifications and entrenchments in the area of ​​Ems and Dollart / Vestingen en schansen in het gebied rond Eems en Dollard . Sollermann printing and publishing house, Leer, p. 105 (no year probably 1992).
  26. ^ Karl-Ernst Behre , Hajo van Lengen : Ostfriesland. History and shape of a cultural landscape. East Frisian landscape. Aurich 1995, ISBN 3-925365-85-0 , p. 156