Erminia has been transformed from the feminine girl in the drawing into a more substantial figure here. Although there are few differences in pose and dress between the painted and the drawn versions, Erminia's physique has become considerably more muscular. The light, fluid chalk strokes of the drawing have been translated into solid lines and defined areas of dense colour. Erminia's facial expression has also been altered from a forlorn, emotional appearance to a more panic-stricken look of shock and fear. The similarities between the sketch and the painting show that Guercino actually had a fully formed idea of how he wanted Erminia to appear before he began to paint her. The changes in mood and technique are largely the result of converting the design from a small drawing into a vast oil painting.
This large dramatic painting illustrates a scene from Torquato Tasso's great epic poem about the Crusades: 'Gerusalemme Liberata' ('Jerusalem Delivered') (1581). Erminia has rushed to the spot where her lover Tancred lies severely wounded. His squire Vafrino kneels over him. The complementary poses, gestures and expressions of the three figures reflect their emotions and the poignancy of the moment. The sombre hues of the landscape enhance the gravity of the event. Cardinal Fabrizio Savelli, Papal Legate of Bologna, commissioned the picture in 1650, but allowed the Duke and Duchess of Mantua to buy it from the artist in 1652.
Guercino was a highly original and lyrical painter and draughtsman. He was born Giovanni Francesco Barbieri in Cento near Bologna (his nickname 'Guercino' means 'squint-eyed'). He was largely self-taught, but was strongly influenced by the bold figure painting of the Carracci family and the dramatic chiaroscuro (light and shadow) of Caravaggio. Guercino chiefly worked in Cento, briefly visited Rome (1621-3), and painted a wide range of subjects, making many exquisite drawings in red chalk and ink. He excelled in daring foreshortening. After the death of his arch rival Guido Reni in 1642 he moved his studio to Bologna.