The Seven Martyrs of Ceuta
Painting in the Chiesa Nuova, Assisi
The event pictured here is summarized in a religious site on the web as follows:
In 1227 Daniel, Minister Provincial of Calabria, together with six companions, Angelo, Samuele, Donnolo, Leone, Ugolino and Nicola, left for the North African missions. They landed in Ceuta, where some Christian merchants advised them not to preach to the Saracens. But they paid no heed to these warnings and proclaimed the Gospel without fear, until they were thrown in prison. There they wrote a letter to the Christians in the region, announcing that they were going to be martyred for the sake of the Gospel. After days of torment in the prison they were taken out and beheaded. Pope Leo X canonised them in 1517. The account of their martyrdom is found in Analecta Franciscana III, pp. 613-616.
I took a look at the cited source, and this narrative summarizes it accurately. As in the Analecta, the painting shows us seven men in Franciscan habits being beheaded at the order of the official that the text calls "the ancient Saracen." The main difference between the painting and the narrative is that the latter says the friars were stripped of their clothing before their executions.
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Photographed at the church by Claire Stracke, shared under Attribution-NonCommercial-ShareAlike license.