 At the death of his father on 28 June 1800, he succeeded as the Prince Reuss of Greiz.After the devastation of Greiz by a fire in 1802, he ordered to rebuild the city in a neoclassical style, and he moved his residence from the Oberes Schloss (Upper Castle) to the Unteres Schloss (Lower Castle), to be more in contact with the people and social life of the Principality.Henry also distinguished himself in his military service to Austria as a field marshal, to the point of being considered one of the best friends of the Emperor Joseph II .