The Sforza Hours is a richly illuminated Book of Hours and one of the finest surviving manuscripts of the Renaissance. It was first made for the Duchess of Milan, Bona Sforza, who died in 1503. The book is outstanding for its rich decoration: an unusually high number of its pages have minutely detailed borders, initials, and vignettes, in addition to many full-page illustrations of biblical scenes and portraits of saints.
The painting in the manuscript was made in two stages. The first artist was the Milanese court painter and miniaturist Giovan Pietro Birago (active 1471–1513). According to a surviving letter, Birago had delivered a substantial part of the book to Bona in 1494, but Fra Gian Jacopo, a friar from the convent of San Marco, stole the remaining 200 or so pages, which included the book’s calendar and the Hours of the Virgin. These stolen pages were later sold by Jacopo in Rome to a certain Fra Biancho, who then gave them to Giovanni Maria Sforzino (d. 1520), the half-brother of Bona’s husband, Duke Galeazzo Maria Sforza (d. 1476).
On Bona Sforza’s death, the incomplete Book of Hours was inherited by her nephew Philibert II, Duke of Savoy (1497–1504), who died the following year. Two years later, Margaret of Austria (d. 1530), his widow, took the book with her when she returned to the north to serve as regent of the Netherlands on behalf of her nephew, the future Holy Roman Emperor Charles V (r. 1519–1556).
In 1517 Margaret commissioned the scribe Etienne de Lale to replace the missing pages of text in the manuscript; and between 1519 and 1521, the Flemish artist Gerard Horenbout (d. c. 1541) replaced the missing decoration, adding 16 full-page illustrations along with two borders. These included a full cycle of the life of the Virgin and illustrations marking the book’s major divisions such as the Penitential Psalms and the Office of the Dead.
Three of the stolen leaves from the manuscript were discovered in the 20th century. All three are now in the British Library’s collections. The first leaf (now Add MS 62977) containing a fragment of a liturgical calendar for 20–30 April and an illustration of the month of May, was acquired by the Library 1984. The second leaf (now Add MS 80800) for October, including a full-page illustration of peasants making wine and nobles hawking, was acquired in 2004 with contributions from the Art Fund and additional support from the Friends of the National Libraries. The third leaf (now Add MS 45722) is an image of the Adoration of the Magi, which originally appeared on f. 97r of the manuscript, facing the text of Sext, or Midday Prayer. It was acquired by the Library in 1941.