The closeness of a work from Rubens' studio in the English Royal Collection, known as Equestrian Portrait of a Knight of the Golden Fleece (Fig. I, Note 1), to two equestrian portraits painted by Van Dyck during his stay in Genoa, from 1621 to 1626 (Figs. 2, 3, Note 2) has led to the identification of the sitter. A number of other pictures from the circle of Rubens and Van Dyck show horses and/or riders in related poses and the dates on some of them reveal them to have been painted before Van Dyck's portraits. This applies to The Riding School by or after Rubens, which is generally dated 1610-12 (Fig. 4, Note 3), a Paradise Landscape by Jan Brueghel of 1613 (Note 4) and Sight dated 1617 by the same artist (Fig.5, Note 5), which features a horseman known as Archduke Albert. A number of undated paintings inspired by the same model include six supposed to be of Archduke Albert (Notes 6, 10), three by Casper de Crayer (Fig. 6, Note 13) and eguestrian portraits of Louis XIII (Note 14) and Ladislaw IV of Poland. Thus it seems likely that these followers of Rubens', Van Dyck included, based themselves on one and the same equestrian portrait by their teacher. Since Van Dyck almost certainly painted the two equestrian portraits in Genoa during his stay in that city, his model or a replica of it must also have been there between 1621 and 1626. In fact, probably at the request of his patrons (Note 17), he often used models by Rubens, who had worked in Genoa for a time in 1606 (Note 16). However, his two equestrian portraits are not based on the only Genoese one by Rubens now known, that of the Marchese Doria (Fig. 7, Note 18), which is very different and has a liveliness quite, unlike Van Dyck's quiet static compositions. The equestrian portrait in the English Royal Collection was bought by George I in 1723 as a Rubens. The sitter is clad in the Spanish costume of the early 17 th century while the towers in the background could be those of Antwerp (Note 36). The sitter has been identified as the Archduke Albert, but he actually bears no resemblance to other portraits of the Archduke, who was also much older than this at the time of Ruberas' stay in Genoa in 1606. The most likely candidate is Ambrogio Spinola (Note 32) , the statesman and general, of whom both Rubens and Van Dyck painted more than one portrait. Spinola was commander of the Spanish troups in the Southern Netherlands, a friend of Rubens and Knight of the Golden Fleece, and he also came from Genoa, where this portrait could have been painted during a visit he made to the city in 1606 (Notes 33, 34). Stylistically too the portrait seems to fit in with the series of portraits painted by Rubens in Genoa in that year. The physiognomy of the sitter is certainly close to that of the known portraits of Spinola (Figs. 8-1, Note 35), while the details of Spinola's life also support the identification. Spinola (1569-1630), who was Marquis of Sesto and Venafro, belonged to one of the group of closely related, families of bankers who held key positions in Genoa. He arrived in the Netherlands around 1602 at the head of a large and unusually well-trained body of troops. In 1603 he provided funds to prevent a mutiny among the Spanish troups and after his capture of Ostend in 1604 he was appointed second in command to Archduke Albert. He was made a Knight of the Golden Fleece on I March 1605 and in the same year he was put in charge of military finances. From 1606 until his departure for Spain in 1628 he was superintendent of the military treasury and' mayordomo mayor' to the Archdukes Albert and Isabella. After the death of Albert in 1621 he became principal adviser to Isabella and thus the most powerful man in the Spanish Netherlands. His amiable character brought him many friends, even among the ranks of the enemy, notably the Princes Maurice and Frederick Henry, with whom he had a great deal of contact during the Twelve Years Truce. It was probably one of them who bought the Portrait of Spinola by Van Miereveld (Fig. 8). After a disappointing mission to Spain in 1628, Spinola was relieved of his command of the Army of Flanders and put in charge of the Spanish troups in Lombardy. He died in his castle in Piedmont in 1630. During the years 1603-5 and later Spinola made several visits to Madrid, where he will undoubtedly have met the powerful Duke of Lerma and probably also seen the equestrian portrait that Rubens painted of him in 1603 (Fig. 12, Note 39). He must also have known of the portraits Rubens painted in Genoa in 1606, since at least three and probably five of them are of members of the Spinola family, while there survives a letter to Rubens from Paolo Agostino Spinola on the subject of portraits (Note 40). All this makes it likely that Spinola would have had his own Portrait painted too and that Rubens may well have painted his first portrait of the man who was to become his lifelong friend as early as 1606. Although Rubens was sometimes irritated by Spinola's lack of interest in his work (Note 41) , he admired him greatly (Note 42). He cultivated Spinola's friendship after his return to Antwerp in 1608 and will doubtless have introduced Van Dyck to him. Van Dyck later painted more than twenty pictures for the five Spinola palaces (Note 43) in Genoa and his work also became known in Madrid via Spinola and his son-in-law Don Diego Felipez Messia Guzman de Legañes, who owned many works by Van Dyck (Note 44). The presumed equestrian portrait of Spinola was much copied, as were other portraits of him by Rubens. Spinola was admired all over Europe and that may have been why other commanders and princes wanted to have themselves portrayed in the same way. The original or a replica may have hung in Spirtola's palace in Brussels, where the first to have seen it would have been Archduke Albert, which may explain the many equestrian portraits of him by Rubens' followeers which were based on it. Another possibility is that Rubens himself may have painted an equestrian portrait of the Archduke very similar to that of Spinola around 1610, but that this is no longer known. Caspar de Crayer of Brussels, a friend, though not a pupil of Rubens, was also influenced by the Spinola equestrian portrait. Furthermore, when he was invited to paint a set of equestrian portraits for the Huis ten Bosch, he sent the young Antwerp painter Thomas Willeboirts Bosschaert to The Hague in his place (Note 46) and it was in this way that Rubens' model came to the Northern Netherlands, where it was copied only once, by Isaac Isacsz. in his equestrian portrait of William the Silent (Note 47). The equestrian portrait of Sigmund III of Poland (Fig. 13), a cousin of Archduke Albert, could also have been painted in Van Dyck's studio in Genoa, which was probably visited by his son Prince Ladislaw in 1624 (Note 48). This picture too still owes much to Rubens' model which Van Dyck used again ten years later for his equestrian portraits of Charles I of England (Fig. 14, Note, 50) and Francisco de Moncada (Note 51).