Alfonso II d'Este succeeded his father, Ercole II, as Duke of Ferrara, Modena, and Reggio. He reigned from 1559 until his death in 1597.
The field armor represented in the portrait is etched with bands of scrolling foliage against a dotted ground; the bands are gilded while the main surfaces of the armor are left white. The armor belongs to a well-defined group of Italian harnesses similarly constructed and decorated which date from about 1560. This one is now in the Kunsthistorisches Museum, Vienna (A 765). [information provided by Stuart Pyhrr, Department of Arms and Armor, MMA; see Ortwin Gamber, "Der italienische Harnisch im 16. Jahrhundert," Jahrbuch der kunsthistorischen Sammlungen in Wien 54 (1958), p. 96]
Other portraits of Alfonso II wearing this armor include one where the sitter is shown in the same pose but as a younger man (Palazzina Marfisa, Ferrara; ill. in Jadranka Bentini, ed., "Signore cortese e umanissimo," , p. 145, erroneously identified as Alfonso I), and one where the subject is depicted full-length (Galleria Estense, Modena; ill. in Luciano Chiappini, "La Corte Estense alla metà del Cinquecento," 1984, between pp. 40 and 41, erroneously identified as Ercole II).