The battle on the Slaak between the Dutch and Spanish fleets during the night of 12-13 September 1631

The Battle on the Slaak of September 1631 was a Dutch naval victory over a Spanish fleet that had attempted to relieve the Spanish garrison on the island of Tholen. The engagement took place at night — a circumstance that made it unusual in Dutch marine painting, where daylight conditions typically prevailed — and Simon de Vlieger's 1633 canvas, painted just two years after the event, is among the earliest pictorial records of the action. Night naval battles presented specific technical challenges for painters: the light sources had to be invented rather than observed, with gunfire and burning ships providing dramatic but unreliable illumination. De Vlieger's solution creates atmosphere through extreme tonal contrast — near-black passages of night sky and water against the violent light of cannon fire and flames. The Rijksmuseum's national collection holds the painting as a document of Dutch naval history.

The night setting requires de Vlieger to abandon his usual atmospheric sky studies and instead orchestrate light from artificial sources — gunfire, burning rigging, lanterns. The tonal extremes of near-black and brilliant flame demand careful management to prevent the composition from fragmenting into disconnected light patches.