Breaking bronze Experimental destruction of Bronze Age metalwork
Bronze Age collections of broken tools and weapons like the Havering Hoard (previous feature) have attracted curiosity for centuries. But how were the pieces broken up? Matt Knight worked with a smith to investigate
Why did Bronze Age people bury metal objects? This question has preoccupied archaeologists for nearly 200 years. Copper-alloy weapons, tools, ornaments, ingots and fragments of casting waste were buried in their thousands in Britain and Europe between 2450bc and 600bc. From rivers and hilltops to settlements and graves, they are found in almost every context. By the Late Bronze Age (1150–800bc) many of these objects were deliberately broken and damaged before deposition. It is common to find large hoards of fragmented axes buried in the ground, or burnt and bent spears and swords thrown into watery places. These deposits are usually interpreted as “ritual”, such as symbolic offerings to gods, or “functional”, typically as stores for metalworkers.
But one curious aspect that has never been fully explored is how such objects were damaged. How does one bend a sword? Or smash up an axe? Is breaking an easy task? Or did it require a set of specific skills and resources? Such questions seem simple enough, but they hold potential to direct and support some of our interpretations surrounding Bronze Age metalwork. If hoards of fragmented objects were indeed scrap intended for recycling, could we expect to find evidence that metalworking knowledge was required in fragmentation? Similarly, if burial and dispersal were symbolic acts, was a specialist involved in damaging the pieces?
From 2014 to 2018 I undertook doctoral research to explore the phenomenon of intentionally damaged and deposited metalwork in southwest England. As I studied over 1,500 objects, it quickly became clear that an approach was needed for how we might identify what was deliberate and what was accidental. Surprisingly little work had been done on this. Often intent is inferred by the obvious nature of the damage: a sword bent in half, for
instance, is thought to be clearly deliberate. But one need only look at the Portable Antiquities Scheme database to see we have thousands of Bronze Age fragments for which it is unclear if they broke through use or intent. My research indicated that other “obvious” indicators of deliberate damage include crushed ornaments, or sockets blocked with other objects, while more ambiguous indicators include notched or “hacked” edges, evidence of burning, or bent tips of spears and daggers.
With the aim of clarifying this picture, I commissioned Neil Burridge, a professional bronze smith, to produce replica swords, spears and axes. These could then be used to test different methods of destruction through wear analysis. The replicas were based on real archaeological artefacts which I suspected had been deliberately damaged. This included a fragmented sword from a hoard from St Erth, Cornwall, and broken spearheads buried in a bog called Bloody Pool on Dartmoor, Devon. A damaged axe was chosen from the St Buryan hoard in Cornwall. Each replica replicawas was produced using a similar similarmetal metal composition to that observed in Late Bronze BronzeAge Age Britain: an alloy of copper and tin, with a small amount of lead.
Heating and hammering
To test what kinds of practical damage swords and spears might suffer, they were used in combat scenarios. This type of wear analysis has become increasingly common, and there have been great insights into how these weapons might have been deployed. In my research swords and spears were used in ways that were both intended and, importantly, unintended to produce damage that may have been caused by accident. By clashing
blades on blades, the sword edges were damaged with deep notches, and by attempting to deflect blows with the flat of the sword blade, the blades became bent. Similarly, using the sword against the spear left scarring damage across the spearhead. Some of this damage was relatively minor or could be repaired. Other damage w was more permanent.
The main thrust of the investigation c concerned testing different ways o of breaking the replica objects. C Conversations with metalworkers a and experimental archaeologists were i immensely useful in this regard; those w who worked regularly with bronze a and understood the metal were able t to contribute ideas about what would a and would not work. They indicated t that material failure might be caused o over an extended period of use or t through cold-hammering, but by far t the most common way things fragment is by heating the bronze to high temperatures and hitting it, either accidentally through hot-working, or for intentional breakage. At high temperatures, tin-bronze will become brittle and will snap under impact and stress. Various metalworkers were able to demonstrate this to great effect as part of their process for recasting and recycling, as they reduced the size of larger objects so they might fit into a crucible. However, this has yet to be fully documented under experimental conditions.
With this in mind, some of the replica swords, spears and axes were heated to 500–600° c; at this temperature bronze starts to turn red hot, though it is below melting point. The objects were then struck with a range of tools, including a bronze hammer and chisel. This required very few blows and achieved fragmentation quickly and effectively. In some cases, there was damage associated with the breakage, such as bending or chisel marks. Archaeologically, these are what might indicate the method for fragmentation. Importantly though, some fragments simply snapped leaving no indication of how the object was broken.
The replica spearhead snapped cleanly into three pieces when struck with a hammer, while the sword was broken into 12 pieces when struck with a hammer and chisel. Two axeheads were heated and struck, which produced interesting results: initial attempts to heat and strike them failed, probably because they were not heated to sufficient temperatures. When heated for longer and struck again, the axes shattered into multiple small mall pieceswith pieces with only the cutting edges surviving as large fragments. This is because the higher temperatures had caused a substantial increase in the brittleness of the metal.
Objects were also left unheated and struck. This was far less effective, requiring many more hammer blows and resulting in greater deformation of the replicas, such as crushing and causing surface damage. Fragmenting a heated socketed axe took only three hammer blows; when a replica was left unheated it took 105 blows to start fracturing!
Skills in mass destruction
Out of this work has come the beginning of a reference collection for comparing archaeological specimens with deliberately damaged replicas. The experimental fragments broken by heating and hitting offer the most compelling parallels, especially when set against the original objects on which they were based.
Thus the surviving incomplete
Bloody Pool spearheads are all broken across the middle of the blade and have generally been considered the result of deliberate breakage; these experiments seem to confirm the method for doing this. The four refitting sword fragments from St Erth also present sharp breaks with no associated damage, such as bending or toolmarks that might have implied how they were broken; the replica sword broke similarly, though evidence for the use of a chisel can be s seen on some of the fragments. It seems l likely the St Erth sword was fragmented b by heating and hitting, with no or l limited use of a chisel.
The highly fragmented replica s socketed axeheads were not comparable with the St Buryan axehead on which they were based, but the fragments could be compared with multiple examples across south-west England and wider Britain. The replica cutting-edge fragments were the largest pieces resulting from fragmentation: these are common finds in the archaeological record, discovered as single finds and in large metalwork hoards. It has been speculated whether these blade edges broke after extensive use or whether they were the result of intent; these experiments certainly indicate that many of the fragments were likely broken deliberately. Of course, it must be conceded that the experiments described here were
intended to produce destruction; more work needs to be done on whether socketed axes may also break this way through long periods of use.
Interestingly, some archaeological parallels were found for the replicas that were not heated before fragmentation. Pieces of spearheads in a late Bronze Age hoard from Stogursey, Somerset, indicate that they may have been broken unheated. This hoard also contains objects that were clearly heated before fragmentation. Therefore, this presents the opportunity to begin to think about how different objects were broken and what it might mean when we see combined practices in a single deposit. In the case of Stogursey, it perhaps speaks to the accumulation of objects over time and the varied methods used to break objects.
So, are skills required to destroy bronze objects before deposition? Yes and no. Certainly it does not take a trained metalworker to stick objects in a fire and hit them with a hammer. And yet, you needed the knowledge and wherewithal to construct a fire, to have the relevant tools available, and to understand the material at play, which all suggests a degree of metalworking expertise. Certainly Neil Burridge’s involvement in the experiments aided enormously, and he could generally predict and pre-empt patterns of fragmentation and damage. It seems likely that Bronze Age smiths would have been central to fragmenting and accumulating the large hoards of metalwork that we encounter archaeologically. Likewise, if objects were being damaged for a specific purpose, such as an offering, there may have h been preconceived ideas about how h people wanted objects to break; metalworkers m would have been essential for f that too.
Of course, deliberately damaging metalwork m is just one aspect to be set in i the wider process of deposition. Starting S from south-west England, it i is possible to begin to recognise variations v in patterns of destruction over o time, linked with different modes of o deposition. The Bloody Pool spearheads s were deliberately broken before b being placed in a bog around 1020–920bc. 1 It is the only such hoard f from the south-west peninsula, but e elsewhere at the same time swords a and spears were also deliberately bent, burnt or broken and deposited in hoards in watery locations, such as bogs, lochs and rivers. Famous examples are known from Wilburton, Cambridgeshire, and Duddingston Loch, Edinburgh, as well as numerous individual finds from the River Thames.
New narratives
As we recognise the intent and processes behind these actions, we can build up narratives surrounding deposition, including who might have been involved, such as metalworkers, and what must have happened to the objects leading up to the event. If heated before fragmentation, perhaps the objects were thrown into water while still hot, adding to the spectacle of deposition as they made a hiss of steam. That this should have occurred at Bloody Pool with no other comparable activity nearby, suggests the communication of knowledge and spread of ideas into this region from further afield. In one sense, whether this might have been an offering to gods, sacrifice of a war booty, or just a way of managing social concepts doesn’t really matter: what is of interest is that there was a common understanding of how objects should be treated and deposited.
From around 950bc some of the hoards of fragmented metalwork became very large, containing hundreds of complete and incomplete objects. These are particularly concentrated in south-east England, but metalwork fragments dating to this period occur
across Britain. They are commonly referred to as “scrap” hoards, and recent investigations into these by Rob Wiseman have indicated that they were probably randomly accumulated, perhaps for recycling. These must have been the result of numerous events where metalwork was deliberately heated and fragmented, perhaps with pieces added and removed over extended periods of time. And yet there are many complete, unbroken objects in these hoards, which might suggest some aspect of selection or deliberate inclusion.
Linked to this, the Portable Antiquities Scheme records large numbers of isolated fragments of swords, axes and other metalwork recovered by detectorists across Britain. Often these are found by chance in unassuming locations, with limited other evidence of prehistoric activity. These fragments often display signs of deliberate breakage, comparable with that produced during the experiments and as seen in the larger hoards, suggesting they may fit into similar practices. Up until now, many of these single fragments have simply contributed to dots on distribution maps. But if we recognise that they may have been part of wider practices of fragmentation and deposition, what can we say then about their deposition? They are usually found in similar types of location to hoards so perhaps they represent the residue of stores of metalwork. Alternatively, they could be a scaled down version of the hoarding practice, acted out through a single object instead of hundreds. ndreds.
We are unlikely ikely ever to be able to say conclusively why so somuchmetalwork much metalwork was deposited. But thinking about how objects were damaged brings new information to old debates, drawing links between comparable practices and enabling new insights into the actions of Bronze Age people.
Matt Knight is curator of the Chalcolithic and Bronze Age collections at National Museums Scotland. Thanks go to Neil Burridge for producing replicas and assisting with the experiments (see www.bronze-ageswords.com), Anthony Harding, Linda Hurcombe (both University of Exeter) and Joanna Brück ( ucd, Dublin), for their support during Knight’s phd, and the ahrc for funding this research. See “Going to pieces: investigating the deliberate destruction of Late Bronze Age swords and spearheads,” Proceedings of the Prehistoric Society (2019) and “The deliberate destruction of Late Bronze Age socketed axeheads in Cornwall,” Cornish Archaeology (2017), both by the author