Corneli(u)s Rudolphus Theodorus, Baron Krayenhoff (Nijmegen, 2 June 1758 – Nijmegen, 24 November 1840) was a physicist, artist, general, hydraulic engineer, cartographer and – against his will and for only a short time – Dutch Minister of War. Biography His father was a hydraulic engineer and soldier in Nijmegen, with brewing as a sideline. Krayenhoff was educated in Nijmegen, Arnhem and Harderwijk. In the latter city he met Herman Willem Daendels, later a fellow-revolutionary. He had been intended to study law, but began to study philosophy and medicine instead (1777–1783). He wrote his dissertations on the theory of the imagination and a medical survey of the dysentery epidemic that raged in Nijmegen in 1783. He established himself as a physician in Amsterdam, after he had declined an offer of a professorate in medicine at Franeker university. He was a member of the Concordia et Libertate genootschap and of Maatschappij tot Nut van 't Algemeen. In the Felix Meritis genootschap he presented physics experiments and lectured on art history, while taking lessons in painting. He refused a request to take charge of organizing military inundations around Amsterdam during the Patriot Revolt of 1785–7. This may have contributed to the fall of Amsterdam to the Prussians in 1787, when they intervened in favor of stadtholder William V. Krayenhoff was an authority on electricity and lightning. The spire of the Grote or Martinikerk (a church in Doesburg) was, in 1782, the first building in the Netherlands to be equipped with a lightning conductor. He and Adriaan Paets van Troostwijk in 1787 won first prize for their article on electricity. In 1791 he became a member of the Hollandsche Maatschappij der Wetenschappen, and in 1808 member of the Royal Institute (a scientific genootschap, one of the predecessors of the Royal Netherlands Academy of Arts and Sciences). The Batavian Republic At the end of 1794 Krayenhoff became involved in revolutionary activities of the Patriots in Amsterdam, while the French revolutionary armies under general Charles Pichegru and general Daendels were invading the Dutch Republic. In October 1794, the revolutionaries attempted an insurrection in Amsterdam, in which Krayenhoff, together with Alexander Gogel was a ringleader (he acted as Military Officer of the Revolutionary Committee). After its suppression he had to flee Amsterdam secretly because he was gathering weapons in Amsterdam. He joined the Patriot Revolutionary Committee with the French headquarters in 's-Hertogenbosch. The French advanced rapidly after