Doria, a wealthy and talented nobleman and art collector, was the son of the powerful Doge of Genoa, Agostino Doria. The painting has parallels in the equestrian portraits by Rubens of the Duke of Lerma (painted in 1603, and now in the Prado Museum Madrid), and Don Pedro Calderon (painted ca. 1611 - 1615 and now in the Royal Collection at Windsor).
The Lerma portrait, with its haughty, richly decorated and armoured rider astride his slowly pacing horse, is so strikingly real that the duke appears to be about to step out of the frame. The horse, clearly a member of the desirable Spanish breed, is very similar in appearance to that of Doria. The perspective of horse and rider, viewed from the front, creates a powerful impression on the observer.
Rubens drew inspiration from the aristocratic and regal equestrian portraits of Titian, particularly his masterpiece depicting the Holy Roman Emperor Charles V armoured and riding forward, lance in hand, at the Battle of Mühlberg.
The horses in these works of art are as important as their riders. Powerful and characterful, they gaze intently at the observer, who feels the strength of their noble gaze as much as that of their authoritative riders. In the portrait of Doria, his sober clothing and background, as well as his thoughtful, even melancholic face, contrast with the artful lighting of the horse and its tail.
It is as if the scene were illuminated by a lightning flash. The horse elevates itself into the levade, one of the movements of classical haute école horsemanship, and rivets the viewer with the intensity of its gaze, while the red favour fastened round Doria's arm flutters like a warning banner in the stiff breeze of a sudden storm. These elements may well have been inspired by the Titian portrait of the Emperor Charles, which also has the stormy, baleful sky and elements of red to indicate the martial nature of the subject.
For these mounted noblemen are all also warriors. Both the Duke of Lerma and Giancarlo Doria bear the insignia of the religious and military order of St James, and the Calderon portrait too has its themes of darkness and martial red. Giancarlo Doria was granted membership to the order by King Philip III of Spain. The equestrian portrait of Giancarlo Doria is a tribute to noble equestrianism.