In July 1751 he was appointed as secretary on Eustatius, which became a free port in 1756 and used more intensively by the Middelburgsche Commercie Compagnie for slave trade on New Spain and the Caribbean islands.

[7] De Graaff held his position until admiral Rodney, leading a large naval force, captured the island in February 1781.

[8] "White puffs of gun smoke over a turquoise sea followed by the boom of cannon rose from the unassuming port on the diminutive Dutch island of St. Eustatius in the West Indies on 16 November 1776.

The guns of Fort Orange on St. Eustatius were returning the ritual salute on entering a foreign port of an American vessel, the Andrew Doria, as she came up the roadstead, flying at her mast the red-and-white-striped flag of the Continental Congress.

In its responding salute, the small voice of St. Eustatius was the first to officially greet the largest event of the century – the entry into the society of nations of a new Atlantic state destined to change the direction of history".