On June 20, 1944, partisans killed a German lieutenant and wounded a soldier at the caffè Nafissi in central Gubbio.
The Germans had threatened strict reprisals on the populace for any attacks on their troops: 40 citizens for every officer and 20 for every soldier.
While the Germans were preparing a withdrawal to the Gothic line, they randomly rounded citizens and despite the pleas by the local bishop, two days later the 40 citizens were massacred under orders by General Dr Johann Karl Boelsen, commander of the 114th Jäger Division.
Those killed included individuals of all ages, both sexes, and diverse lines of work.
The original plan was a simple and sober mausoleum circumscribed by 40 slender cypress trees.