Dutch Aristocrat.

An early and fervent supporter of the American cause, he opposed Great Britain’s use of Waldeck’s Scottish Brigade.

Sent a translation of his pamphlet, Advis door Jonkheer Johan Derk van der Capelen tot den Pol over het verzoek van zijne Majesteit den Koning van Groot-Brittanïé, Raakende het leenen der Schotsche Brigade … (1775), to Franklin in 1778.

Published Dutch translations of Dr. Richard Price’s Observations on the Nature of Civil Liberty and Justice and the Policy of the War with America (1776) and Additional Observations … (1777).

Corresponded with Jonathan Trumbull, governor of Connecticut, and with William Livingston, governor of New Jersey.