Pensionary of Amsterdam.

A proponent of trade between Amsterdam and America, Charles-Guillaume-Frédéric Dumas frequently referred to him as “notre ami,” our friend.

Established a secret contact with William Lee, American commissioner in Germany. Was in collusion with Jean de Neufville, the Amsterdam banker who, with Lee, signed the 1778 Dutch-American draft commercial treaty that gave the British a pretext to open hostilities against the Netherlands. The charges brought against him in 1780 for his role in the affair were eventually dropped (March, 1781).