Ugolino di Nerio, 'The Betrayal of Christ', possibly 1325-8

These panels were once part of a large altarpiece made by the Sienese painter Ugolino di Nerio for the high altar of the Franciscan church of Santa Croce in Florence. In 1566 it was removed and replaced with a Crucifix. The altarpiece focuses on the Passion of Christ (his torture and crucifixion) and the Resurrection – an appropriate theme, as the church was dedicated to the Holy Cross. The imagery of the altarpiece was a suitable backdrop to the church’s annual procession of a relic of the Cross.

Although the altarpiece was later dismantled and its panels are now in collections around the world, we have a good idea of how it looked originally. Drawings made in the late eighteenth century show the altarpiece when it was in the friary connected to the church. At that time, Ugolino’s signature was noted on the altarpiece’s frame. Technical analysis of the panels, carried out at the National Gallery, revealed where the panels were connected to each other, and proves the drawing must be an accurate representation of their original arrangement.

The main tier followed the conventional pattern for altarpieces in fourteenth-century Italy, with an image of the Virgin and Child placed centrally and flanked by images of saints (in this case, three on either side painted within pointed arches). The panel with the Virgin and Child does not survive, but three of the panels with saints are now in the Gemäldegalerie, Berlin. Angels were painted in the spandrels of each panel, and those once above Saint Louis of Toulouse and those once above Saint Francis are in our collection.

Above this main tier of images was another row of saints, smaller in scale and framed in six sets of pairs; Saints Bartholomew and Andrew and Saints Simon and Thaddeus are in our collection. The uppermost tier consisted of six pinnacle panels, three on either side of a central image which probably showed the Crucifixion , itself topped by a Blessing Redeemer (Christ making a blessing gesture). Three of the pinnacle panels – Isaiah, Moses and King David – are in our collection.

The lowest layer sat beneath the main tier: the predella. It was originally painted on one continuous piece of horizontal wood, but was later cut into seven individual scenes, all of which survive. We have four – The Betrayal of Christ, The Way to Calvary, The Deposition and The Resurrection – and three are in the Metropolitan Museum of Art, New York.

There is no known dated painting by Ugolino. The altarpiece was probably commissioned by four brothers belonging to the Alamanni family; letters written to their descendants in the sixteenth century seem to refer to their coats of arms on the altarpiece, and the family seem to have had rights over the church’s high altar. It is likely to have been in position by 1326, the year that commemorated one hundred years since Saint Francis’s death, or 1328, the centenary of his canonisation.

There are differences in the quality of the painting between the predella panels in particular, which suggests the involvement of more than one artist. Indeed it was not unusual for a workshop of artists to collaborate on a work of this scale. Ugolino may have used his family workshop to complete this commission.