Iron Shield Boss

This object is called an umbo, which is essentially an iron shield boss. Shield bosses are fixed to the middle of a shield and serve as protection for the shield-bearer’s hand. They were typically made out of wood or, as in this case, iron. The residue of the wooden shield can still be seen on the back of this shield boss that traces back to the seventh century.

3D model of the Iron Shield Boss

The design of shield bosses differs from culture to culture, but this specific design can be linked to the Franks (S. Aarts, personal communication, March 1, 2023), who were Germanic people living in modern-day Germany, Belgium, and the Netherlands. As Frankish soldiers were known for their military prowess and combat skills (James, 1991), one may assume the deep dents of this shield boss were a result of fierce battles it served in. Yet, a brief examination of the site it was found in, the practice of grave goods and the Merovingian dynasty, exposes nuances in how and why the dents came to be.

This object belongs to the following theme:



Place of Origin
Pasestraat, Borgharen, Maastricht,
The Netherlands

Time Period of Use (ca.)
601 – 700 CE


Dimensions (cm)
Diameter: 20

3D Model

Canon EOS 250D

Processing software
Agisoft Metashape Professional Edition

Lea Stieg & Shani de Wit

Bobo and the mystery of his umbo’s dents

Villa and burial site Borgharen

This shield boss was found in a grave in a Merovingian burial site in the town Borgharen. It is an archaeological site north of Maastricht known as “Op de Stein” or villa Borgharen, where remains of both a Roman villa and a burial site have been found (de Kort et al., 2016; Dijkman, 2003; Lauwerier, Müller & Smal, 2011). The current understanding is that the villa was mainly in use during the second century, before being used as a burial site by the sixth century (de Kort et al., 2016). After two rounds of archeological research in collaboration between the Cultural Heritage Agency of the Netherlands, Maastricht University and the University of Amsterdam, a total of 24 graves were discovered, one of which belonged to a 50-59 year old man called Bobo, as indicated by the name inscribed on the belt buckle found in his grave (De Kort et al., 2016; Dijkman, 2003; Lauwerier & de Kort, 2014). Along with at least 10 other objects, this is also where our dented umbo was discovered (Dijkman, 2003).

Illustration of Bobo’s grave and some of his grave goods. Illustration by Lea Stieg

Grave goods and a man called Bobo

The placement of goods in graves is not an uncommon phenomenon. It is a practice that goes far back in time and is observed in a range of different cultures across the world (Härke, 2014). Particularly graves throughout Europe dating back to the Middle Ages have been discovered containing goods as well, no less around Maastricht in the 7th century (Dijkman, 2003), though this practice never appeared to have been uniform throughout the continent or time period (Härke, 2014). One pattern that did occur, is that depending on the gender of the deceased, certain types of goods are more likely to be found in the graves (Härke, 2014). While dress items were common for female graves, male graves often had weapons and tools. This often also included a knife and a belt buckle (Härke, 2014), the latter applying to Bobo. In Western Europe during the Merovingian period, common grave goods can be placed into five categories: parts of clothes, accessories, containers, weapons, personal items and care (Lauwerier et al., 2011). Under weapons, shield bosses were particularly prevalent, for which this shield boss falls in line, though not its condition of being dented. 

The varied theorized reasons associated with the phenomenon of burial goods can suggest why Bobo was buried with this iron shield boss, and possibly also make sense of its dents. Härke (2014) identifies three common domains which archeologists and historians have named as motivations for this practice: religion, legality and social status, the latter two appearing the most relevant here.

How the umbo may have acquired damage before. Illustration by Robbie McSweeney

Legality can be understood through a range of reasons, one being the case that the item was an inalienable object (Härke, 2014). Such an object cannot be inherited, sold or given, hence ending up in the grave (Härke, 2014). Another possibility is how the umbo may have been regarded as a high-status weapon that has been passed down generations, making it a “collective possession” (Härke, 2014). This implies that the shield boss may not be Bobo’s and was passed down to him as the final owner, joining him in his grave.

Social status offers another few avenues to understand the story behind the umbo. The practice of potlatch involves destroying accumulated wealth as a display of privilege or influence (Härke, 2014). Consequently, burial goods may have been consumed during the funeral, before being placed in the deceased’s grave. Perhaps the dents in the iron boss indicate such use during the funeral before it turned into one of Bobo’s grave goods. Next to this, some burial goods are supposed to serve as a metaphor that reflect the deceased’s life or a particular event in their life (Härke, 2014). This is related to the common belief at the time that memory is stored in objects and not in the mind. Therefore, the umbo may have a very context-specific meaning that represents a part of Bobo, sending it into the grave with him.

Possible causes of the dents

So, while a shield boss might not be a particularly unique object for a grave good, this specific umbo still brings up a few questions and mysteries with its deep dents. Though the shield boss is an object of war and heavy combat, historians would beg to differ as the 7th century was a relatively peaceful period around Borgharen, with no wars or other violent disputes (S. Aarts, personal communication, March 1, 2023). While the Frankish soldiers were known for their military knowledge as well as their ferocious combat skills (James, 1991.), their military conquest subsided in the 7th century with the establishment of the Merovingian dynasty (Gaery, 1988). The Merovingian dynasty expanded primarily in Western Europe, specifically in the areas that are now France, Germany, Belgium, the Netherlands, and Switzerland. At its peak, the Merovingian Empire stretched from the Pyrenees Mountains in the south to the North Sea in the north, and from the Atlantic Ocean in the west to the Rhine River in the east.

About the Merovingian Dynasty

Consequently, if the dents were a result of heavy combat, it would be from a different time before being handed down to Bobo over generations, making it a collective possession. Otherwise, it makes sense to speculate that the dents came to be as a result of the aforementioned burial practices. The practice of potlatch may mean the shield was used during Bobo’s funeral, resulting in it acquiring dents. Perhaps its dents signify an aspect of Bobo’s life, that he enjoyed engaging in sword fighting or was particularly fond of this umbo, whether it belonged to him originally or not. This could fall in line with grave goods serving as metaphors of the deceased. 

Another imaginative assumption could be that the dents were caused on accident instead of actual combat. It could be that the metal simply got hot while being in the immediate vicinity of the heating system of the villa, became soft and thus more vulnerable to denting. But considering that metal can only be processed above the heat of 500 degrees, this would have had to be an extraordinary circumstance or accident.

Bobo’s legacy

We may not be able to uncover exactly how the dents of the umbo came to be, neither who Bobo was and what life he lived. Yet, it gives us a chance to reflect on the burial practices of the Franks during the Merovingian period, in light of the Daily Life and Death theme that this umbo falls under. Moreover, Bobo turned into a character with a backstory (Dijkman, 2003), being humanized and popularized in the region, along with Itta from Itteren (de Lange, 2018). Bobo’s character was drawn up to promote the archeological site and research being conducted at Borgharen (Lauwerier et al., 2011), but was never exactly associated with the damaged shield boss as one of the grave goods he was found with… until now.

Written by Lea Stieg & Shani de Wit