TETHART PHILIP CHRISTIAN HAAG (KASSEL 1737 - THE HAGUE 1812) Figures in a carriage led by agitated horses signed and dated 1785 (lower right) oil on panel 47 x 39 cm (18 1/2 x 15 in) Tethart Philipp Christian Haag was a portraitist and a horse painter, and in 1760 succeeded his father as court painter to Stadtholder Prince William V. In 1774, on the founding of the Prince's picture gallery at the Buitenhof in The Hague, Tethart became the director and curator of this first public museum in the Netherlands, later known as the Prince William V Gallery.