The damage wrought on soldiers’ bodies and psyches by the rapid-fire machine guns and heavy artillery of World War I was unprecedented. As noted by Sophie Delaporte, ‘Never before had bodies been annihilated, mutilated, and made ill on such a scale’. In addition to 10 million military war dead, the conflict left 7 million invalids across Europe, with many more who were deeply emotionally traumatised. In response, governments and militaries worked towards the rehabilitation, recovery and reintegration of disabled soldiers into society, as much as was possible. Advances in plastic surgery, psychology and prosthetics all facilitated this process. This elaborate prosthetic forearm is an example of that effort. Attached to the body via an intricate system of straps and harnesses, it is a finely designed and manufactured piece, constructed to allow the wearer to grasp a pen between the thumb and fingers on the left hand, which are made of metal and lined on the underside in cork. It is clear from its construction that this prosthesis was designed for work in a ‘profession liberale’ rather than manual labour. This arm was conceived by the French labour scientist Jules Amar. Amar had led a laboratory at the Conservatoire national des arts et métiers (National Conservatory of Arts and Crafts) in Paris devoted to the study of the human body in motion, particularly at work, which was redirected to advancing the development of prosthetic limbs after the outbreak of the war. This object shows not just the legacy of war trauma, but also the previously hidden histories of disability contained in European museum collections.