James III of Scotland, RIP, and the Trinity Altarpiece

King James III of Scotland died at the Battle of Sauchieburn on June 11, 1488, fighting against Scottish rebels, including his son who would succeed him as King James IV of Scotland. One reason to highlight his death is his portrait in the Trinity Altarpiece painted by Hugo van der Goes, which is on display at the National Galleries Scotland on permanent loan from the Royal Collections:

These panels formed part of one of the most important altarpieces ever painted for a Scottish chapel, and are thought to have been the wings of a triptych. The work was commissioned by Edward Bonkil, Provost of the Collegiate Chapel of the Holy Trinity in Edinburgh. (The chapel was demolished in 1848 to make way for Waverley Station.) The missing central panel possibly showed the Virgin and Child Enthroned, and may have been destroyed during the Reformation. When open, the wings show a devout King James III with his elder son and his queen Margaret of Denmark, accompanied by Saint Andrew and Saint George. The lion rampant on the king’s coat of arms is reversed in deference to the holy figures on the missing central panel. The closed wings feature a vision of the Holy Trinity appearing to the kneeling Edward Bonkil.

You may see the entire panel including his portrait here. The image I'm displaying (Public Domain) is found here.

Note that his son James IV, who also died in battle (at the Battle of Flodden on September 9, 1513), repented of his participation in the death of his father and had Masses said for his soul. According to sources cited in James IV's Wikipedia article: 

James IV bore intense guilt for the indirect role which he had played in the death of his father. He decided to do penance for his sin, constantly wearing an iron belt around his waist, next to the skin, to which he added weight every year throughout his life.[17][18]

James III was entombed in Cambuskenneth Abbey.