Krul was employed on 19 October 1778 by the Dutch East India Company and stationed on the small Dutch isle of Saint Eustatius in the West Indies which provided a neutral port and naval support for various cargo and other ships which arrived and departed on a daily basis during the American Revolutionary War. The Dutch, though their ports were protected by their neutral status, were at the center of the arms trade with the former British colonies and were supplying them via this isle with nearly half of their military supplies. This sort of trading with Britain's enemies is what instigated the Fourth Anglo-Dutch War where Admiral Rodney was subsequently sent to Saint Eustatius (and other Dutch possessions) in the West Indies in February 1781 to neutralize the operation. Shortly after he had captured Saint Eustatius, lying only 50 miles north of British Saint Kitts, Rodney learned that a fleet of thirty cargo ships, richly laden with sugar and other commodities, had just sailed for Holland, under the escort of Admiral Krul and his flag-ship, "Mars", a man-of-war. Rodney immediately dispatched three ships, HMS "Monarch", "Panther" and "Sybil", under the command of Admiral Francis Reynolds, to give chase and capture the enormous 30 vessel prize, with orders to pursue them no further than the latitude of Bermuda.