A representation of the naval Battle of Actium, 2 September 31 BC, which took place off the western coast of Greece. Octavian, through this decisive victory over the combined forces of Mark Anthony and Cleopatra, became master of the Roman world. An account of the battle given in Virgil's 'Aeneid', was translated into English in the late 17th century and may have been the inspiration for this commission.

The artist painted six known battle scenes through his life of which this is the earliest. Produced while he was living in England, it was probably for an English patron and shows the close combat between the opposing fleets. The battle was hotly contested until Cleopatra fled with her Egyptian galleys. Anthony followed her with a few ships and eventually surrendered to Octavian. In this dramatic Baroque interpretation the figures wear a 17th-century Roman costume. Some of the soldiers wear armour and plumed helmets. The galleys have ornate figureheads of fantastical creatures, with their flags and pennants billowing. Although the artist had some knowledge of Mediterranean ports and shipping, the galleys in this picture more closely resemble Dutch fluyts, since they are squat instead of long and slender.

As the battle rages the galley farthest right bears soldiers preparing to fire with bows and arrows. The figure in the prow holds a long spear towards the opposing galleys, an action repeated in the galley in the centre. The clearly delineated men rowing the galleys have shields to protect them. In the foreground the prow of a sunken galley, carved as a bird, rises above the water. Soldiers have been flung in the water or are clinging to the mast. The woman on the ornate barge may represent Cleopatra, her outstretched arms gesturing in despair at the battle lost. She wears 17th-century rather than Egyptian dress and is attended by women exotically dressed with turbans and feathers. The soldier in the prow of the barge, cloak billowing behind him, bears a long spear, and to his left is a full-size naked figure of a woman standing on a globe, who may represent Fortune. Fortune was the mistress of the sea, feared by seafarers everywhere. Amongst her attributes was a billowing sail, as in this painting. Her presence further underscores Cleopatra's fate, since the battle was a turning point in the history of Egypt.

Castro was a Flemish painter of Portugese extraction and master of the Antwerp Guild of St Luke in 1664-65. His first name sometimes appears as 'Laureys'. The artist has signed and dated the painting on the shield of the sinking ship in the foreground. This is his earliest known dated work.