It shows the conspiracy led by Giovanni Andrea Lampugnani, Gerolamo Olgiati, Carlo Visconti and Cola Montano to overthrow the tyranny of Galeazzo Maria Sforza, killed on 26 December 1476 in Santo Stefano church in Milan.
It appeared in the Piccolo inventario dei dipinti at the villa di Lesa with the title "A canvas representing an episode in the History of Milan", before entering the collection of Manzoni's stepson Stefano Stampa, from whom it was then acquired by its present owner.
[1] Hayez himself chose the then little-known subject, having found it in Alessandro Verri's 1779 tragedy La congiura di Cola Montano and by his reading of Niccolò Machiavelli's Histories, specifically a section of the latter entitled "Segretario Fiorentino Libro Settimo delle Istorie" – that title appears in his notes and shows that Histories was his main source.
[1] The highly theatrical composition places Montano in the foreground, kneeling at the foot of a statue of Saint Ambrose (never actually in Santo Stefano but included for a narrative purpose), perhaps praying for his protection.
[3] It also draws on the ideological ferments of the early 19th century, opaquely but decisively dressing Risorgimento ideas in a glorification of the "myth of the Carbonara youth".