At the age of 24 he was married to Catrina de Hoogh on 8 February, at Den Haag, and they had a son, Arie Hendrik Willem Krul.

[4][5][6][7] In the years 1742–1744 Krul made a voyage to Batavia as a lieutenant in the service of the Dutch East India Company on the ship Anna.

[10][11] 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.

[e] 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,[f] with orders to pursue them no further than the latitude of Bermuda.

During the ensuing engagement on 4 February 1781 Krul, with a single warship, resolved to uphold the honor of the Dutch flag and confront his pursuers with the hopes of giving the cargo ships a chance to escape.