Joan Melchior Kemper (1776 - 1824) by D.P.G. Humbert de Superville, c. 1815. Former Patriot Kemper was the author of the proclamation with which Prince William of Orange presented himself as 'William I, sovereign lord' on 2 December 1813, a few days after arriving in the Netherlands. In it William I promised a constitution guaranteeing the freedom of his subjects. As a professor the jurist Kemper was the mentor of many later politicians such as Thorbecke and Groen van Prinsterer. In 1817 Kemper became a member of the Lower House. Kemper's decorations are the symbols of Commander of the Orde van de Nederlandse Leeuw. The order was established in 1815. Kemper was a personal friend of the painter. Humbert gave Kemper's daughters drawing lessons. And Kemper had ensured that Humbert was appointed lecturer at Leiden University in 1814.