Trebuchet test at the University of Toronto Back Campus, 12 April 1991. Figure 1 in W. T. S. Tarver, “The Traction Trebuchet: A Reconstruction of an Early Medieval Siege Engine,” Technology and Culture, Vol. 36, No. 1. (January 1995)
In the early middle ages, Europeans learned about a much simpler technology than the ancient catapult: the trebuchet powered by teams of men and women pulling ropes. This weapon was not so long-ranged or accurate but it had no delicate skeins of rope or expensive metal parts so it suited conditions in a poor and small-scale world. After it entered European history at the Slav and Avar siege of Thessalonike in 597, it quickly became the most popular siege engine in Europe (although it is possible that a few engineers remembered how to make engines powered by giant bows or skeins of rope for long-ranged, accurate shooting). These ‘traction trebuchets’ have not been as often reproduced as ancient catapults, but there have been a few attempts:
In the summer of 1988, after frustrating winter-long attempts to build an arrow-shooting torsion ballista, and having been inspired by Randall Rogers at the Twenty-third International Congress on Medieval Studies at Western Michigan University in Kalamazoo (hereafter Medieval Congress in Kalamazoo), I constructed a simple traction trebuchet which could throw a fist-sized rock 120 m. [Several larger versions followed culminating in one which the university authorities did not approve of]. In August, it was tested at Cooper’s Lake Campground in Pennsylvania, where a large field beside an archery range was available and where volunteers could be mustered for the trials.
– W. T. S. Tarver, “The Traction Trebuchet: A Reconstruction of an Early Medieval Siege Engine,” Technology and Culture, Vol. 36, No. 1. (January 1995), p. 147 n. 52
I am sure that there were volunteers at Cooper’s Lake in August at any time between 1972 and 2019, and there will be again in 2021!