Diego Martelli at Castiglioncello

Diego Martelli was among the most important figures associated with the Macchiaioli movement — a critic, intellectual, and patron who hosted the painters at his estate at Castiglioncello on the Tuscan coast. Fattori's 1870 portrait of Martelli relaxing at Castiglioncello is a landmark in Italian art: it depicts the movement's greatest champion in the landscape that gave the group some of their most characteristic subjects. The casual, outdoor setting — Martelli seated or reclining, the sea or countryside visible behind him — reflects the movement's values of directness, informality, and the integration of figures into observed light conditions. Degas would later paint Martelli in a similar spirit during the Frenchman's visit to Florence. The image distils the philosophical and personal bonds between the Macchiaioli and the cultivated intellectual who championed them.

The outdoor setting allows Fattori to apply Macchiaioli principles to portrait making with particular rigour — the figure is observed under real, variable light rather than the controlled conditions of a studio. Bold tonal contrasts describe the coastal light. The composition is informal, the sitter's posture relaxed rather than formally composed.