Fascinating archaeological find becomes a source of knowledge

The Bavarian State Office for the Preservation of Historical Monuments (BLfD) has sent a rare artefact from the Middle Bronze Age to Berlin for examination using cutting-edge, non-destructive methods. It is a 3,400-year-old bronze sword, unearthed during archaeological excavations in Nördlingen, Swabia, in 2023. Experts have been able to determine how the hilt and blade are connected, as well as how the rare and well-preserved decorations on the pommel were made. This has provided valuable insight into the craft techniques employed in southern Germany during the Bronze Age. The BLfD used 3D computed tomography and X-ray diffraction to analyse internal stresses at the Helmholtz-Zentrum Berlin (HZB), as well as X-ray fluorescence spectroscopy at a BESSY II beamline supervised by the Bundesanstalt für Materialforschung und -prüfung (BAM).

Measuring guests are part of everyday life at HZB and BAM; they come to examine their samples using the most modern methods. However, measurement campaigns on extraordinary cultural treasures such as the decorated octagonal sword from the Middle Bronze Age are not an everyday occurrence. Dr Johann-Friedrich Tolksdorf, regional representative of the BLfD, and his colleague Beate Herbold, a restorer, brought this sword to Berlin. It comes from a grave in Nördlingen and is more than 3,400 years old. It is so well preserved that it still shines in places and the elaborate decorations on the pommel and pommel plate are clearly visible. The blade is also still almost sharp.

How was the handle connected to the blade?

‘We had specific questions that we wanted to investigate using three different methods at HZB, and with the help of BAM,’ says Dr Johann-Friedrich Tolksdorf. Restorer Beate Herbold explains: ‘Such swords were very costly to manufacture. We wanted to find out how the handle was connected to the blade at that time and how the decorative patterns were incorporated at that time.’ This question was investigated in the HZB computer tomography laboratory, where Dr Nikolay Kardjilov and his team created a three-dimensional X-ray image of the sword. ‘The CT scan shows that the blade was clamped into the hilt with a tang, i.e. an extension of the blade, and riveted. The resolution of the CT scan is so high that we can even examine the material and the traces of the decorative work,’ says Tolksdorf.

What material was used for the decorative patterns?

The pommel and pommel plate are adorned with deep grooves which form a geometric pattern. These grooves contained what appeared to be a different material. It remained unclear what this material was. However, the team was able to find out more at the BAMline at BESSY II, operated by BAM. Dr Martin Radtke examined the sword using X-ray fluorescence spectroscopy. ‘We irradiate the surfaces on the pommel with intense synchrotron radiation. This excites atoms in the material, causing them to emit element-specific X-rays, which we then measure. We can detect even the tiniest traces of elements,‘ says Radtke. The initial results show that the inlay work on the pommel and pommel plate consisted of copper wires that were pieced together. ’Based on its appearance, I actually expected tin to have been used for these decorations, as tin is softer and easier to work with than copper, so that was a surprise, which also shows how highly developed craftsmanship was even back then,‘ says Beate Herbold. Traces of tin and, in some places, a little lead, which probably came from the bronze alloy, were also detectable. ’We are familiar with this type of inlay work using copper wires in bronze from other finds,’ says Tolksdorf. ‘To make the reddish copper stand out better from the gold-coloured bronze, it may have been patinated, i.e. chemically blackened, for example with urine.’

How were the craftsmen working?

The question of the craftsmanship involved in the manufacturing process was investigated in Dr Manuela Klaus's X-ray laboratory. There, it is possible to perform a so-called internal stress analysis – i.e. to detect pressure and tension in the crystalline surfaces. ‘This provides information about the manufacturing processes, because typical changes to the crystalline structures occur during heating, quenching, casting, hammering and forging,’ says Manuela Klaus.

Outlook:

The thorough evaluation of the measurement data will take some time, after which the experts plan to publish their results and conclusions. ‘We hope that we will also be able to reconstruct whether this sword was made in a specific workshop, for example – so far, we can only assume that it was manufactured in southern Germany, one of the two main areas where octagonal swords were prevalent in the Bronze Age in Germany,’ says Tolksdorf.

‘The collaboration with the Helmholtz-Zentrum Berlin and the Bundesanstalt für Materialforschung und -prüfung has been very fruitful. Using state-of-the-art measurement methods, we can understand how metal was worked almost three and a half millennia ago, with astonishing precision and highly developed skills. As much attention as the discovery of the Nördlingen bronze sword has already received, its scientific examination makes it even more significant for us. Only then does a fascinating find become a valuable source of knowledge,’ says Prof. Mathias Pfeil, General Curator of the BLfD.